diff --git a/apps/api-extractor/config/heft.json b/apps/api-extractor/config/heft.json
index 64cf00b82a3..0b965cec36a 100644
--- a/apps/api-extractor/config/heft.json
+++ b/apps/api-extractor/config/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   "extends": "decoupled-local-node-rig/profiles/default/config/heft.json",
 
diff --git a/apps/heft/src/schemas/heft-legacy.schema.json b/apps/heft/src/schemas/heft-legacy.schema.json
index 79143dcfd8f..45d26aa00f0 100644
--- a/apps/heft/src/schemas/heft-legacy.schema.json
+++ b/apps/heft/src/schemas/heft-legacy.schema.json
@@ -20,7 +20,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },
 
diff --git a/apps/heft/src/schemas/heft.schema.json b/apps/heft/src/schemas/heft.schema.json
index d4a3ce5719d..cba91630724 100644
--- a/apps/heft/src/schemas/heft.schema.json
+++ b/apps/heft/src/schemas/heft.schema.json
@@ -104,7 +104,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },
 
diff --git a/apps/heft/src/schemas/node-service.schema.json b/apps/heft/src/schemas/node-service.schema.json
index ee9700a5308..67af1bc48a9 100644
--- a/apps/heft/src/schemas/node-service.schema.json
+++ b/apps/heft/src/schemas/node-service.schema.json
@@ -13,7 +13,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },
 
diff --git a/apps/heft/src/schemas/templates/heft.json b/apps/heft/src/schemas/templates/heft.json
index 087762787dd..870a1a538a3 100644
--- a/apps/heft/src/schemas/templates/heft.json
+++ b/apps/heft/src/schemas/templates/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/heft.json",
 
diff --git a/apps/lockfile-explorer-web/config/heft.json b/apps/lockfile-explorer-web/config/heft.json
index 5a56a867004..e031c98a5c5 100644
--- a/apps/lockfile-explorer-web/config/heft.json
+++ b/apps/lockfile-explorer-web/config/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   "extends": "local-web-rig/profiles/app/config/heft.json",
 
diff --git a/apps/lockfile-explorer/config/heft.json b/apps/lockfile-explorer/config/heft.json
index 858939560cb..425aa0a60d9 100644
--- a/apps/lockfile-explorer/config/heft.json
+++ b/apps/lockfile-explorer/config/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   "extends": "local-node-rig/profiles/default/config/heft.json",
 
diff --git a/apps/lockfile-explorer/config/node-service.json b/apps/lockfile-explorer/config/node-service.json
index c1cedd887ee..ba18df29aaf 100644
--- a/apps/lockfile-explorer/config/node-service.json
+++ b/apps/lockfile-explorer/config/node-service.json
@@ -8,6 +8,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/serve-command.json",
 
diff --git a/build-tests-samples/heft-web-rig-library-tutorial/config/api-extractor.json b/build-tests-samples/heft-web-rig-library-tutorial/config/api-extractor.json
index 8fcd66198e4..4cd36c3e066 100644
--- a/build-tests-samples/heft-web-rig-library-tutorial/config/api-extractor.json
+++ b/build-tests-samples/heft-web-rig-library-tutorial/config/api-extractor.json
@@ -8,6 +8,8 @@
    * Optionally specifies another JSON config file that this file extends from.  This provides a way for
    * standard settings to be shared across multiple projects.
    *
+   * To delete an inherited setting, set it to `null` in this file.
+   *
    * If the path starts with "./" or "../", the path is resolved relative to the folder of the file that contains
    * the "extends" field.  Otherwise, the first path segment is interpreted as an NPM package name, and will be
    * resolved using NodeJS require().
diff --git a/build-tests/heft-fastify-test/config/node-service.json b/build-tests/heft-fastify-test/config/node-service.json
index 67a768f75d6..62e904d49ce 100644
--- a/build-tests/heft-fastify-test/config/node-service.json
+++ b/build-tests/heft-fastify-test/config/node-service.json
@@ -8,6 +8,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/serve-command.json",
 
diff --git a/build-tests/localization-plugin-test-01/config/heft.json b/build-tests/localization-plugin-test-01/config/heft.json
index abfbce326e5..4d81cfade08 100644
--- a/build-tests/localization-plugin-test-01/config/heft.json
+++ b/build-tests/localization-plugin-test-01/config/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   "extends": "local-node-rig/profiles/default/config/heft.json",
 
diff --git a/build-tests/localization-plugin-test-02/config/heft.json b/build-tests/localization-plugin-test-02/config/heft.json
index e97c7b80c59..6d560f084ee 100644
--- a/build-tests/localization-plugin-test-02/config/heft.json
+++ b/build-tests/localization-plugin-test-02/config/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   "extends": "local-node-rig/profiles/default/config/heft.json",
 
diff --git a/common/changes/@microsoft/api-extractor/config-file-null_2025-04-16-01-15.json b/common/changes/@microsoft/api-extractor/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..9d8d259566d
--- /dev/null
+++ b/common/changes/@microsoft/api-extractor/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "patch",
+      "packageName": "@microsoft/api-extractor"
+    }
+  ],
+  "packageName": "@microsoft/api-extractor",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/common/changes/@microsoft/rush/config-file-null_2025-04-16-01-15.json b/common/changes/@microsoft/rush/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..008eda99f5b
--- /dev/null
+++ b/common/changes/@microsoft/rush/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "none",
+      "packageName": "@microsoft/rush"
+    }
+  ],
+  "packageName": "@microsoft/rush",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/common/changes/@rushstack/heft-api-extractor-plugin/config-file-null_2025-04-16-01-15.json b/common/changes/@rushstack/heft-api-extractor-plugin/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..4170d8d7520
--- /dev/null
+++ b/common/changes/@rushstack/heft-api-extractor-plugin/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "patch",
+      "packageName": "@rushstack/heft-api-extractor-plugin"
+    }
+  ],
+  "packageName": "@rushstack/heft-api-extractor-plugin",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/common/changes/@rushstack/heft-config-file/config-file-null_2025-04-16-00-37.json b/common/changes/@rushstack/heft-config-file/config-file-null_2025-04-16-00-37.json
new file mode 100644
index 00000000000..f574e7084c1
--- /dev/null
+++ b/common/changes/@rushstack/heft-config-file/config-file-null_2025-04-16-00-37.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/heft-config-file",
+      "comment": "Allow use of the value `null` to discard any value set for the property from a parent config file..",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@rushstack/heft-config-file"
+}
\ No newline at end of file
diff --git a/common/changes/@rushstack/heft-node-rig/config-file-null_2025-04-16-01-15.json b/common/changes/@rushstack/heft-node-rig/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..75e1eee2dbc
--- /dev/null
+++ b/common/changes/@rushstack/heft-node-rig/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "patch",
+      "packageName": "@rushstack/heft-node-rig"
+    }
+  ],
+  "packageName": "@rushstack/heft-node-rig",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/common/changes/@rushstack/heft-sass-plugin/config-file-null_2025-04-16-01-15.json b/common/changes/@rushstack/heft-sass-plugin/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..cd261e0234d
--- /dev/null
+++ b/common/changes/@rushstack/heft-sass-plugin/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "patch",
+      "packageName": "@rushstack/heft-sass-plugin"
+    }
+  ],
+  "packageName": "@rushstack/heft-sass-plugin",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/common/changes/@rushstack/heft-typescript-plugin/config-file-null_2025-04-16-01-15.json b/common/changes/@rushstack/heft-typescript-plugin/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..f40ba849fc9
--- /dev/null
+++ b/common/changes/@rushstack/heft-typescript-plugin/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "patch",
+      "packageName": "@rushstack/heft-typescript-plugin"
+    }
+  ],
+  "packageName": "@rushstack/heft-typescript-plugin",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/common/changes/@rushstack/heft-web-rig/config-file-null_2025-04-16-01-15.json b/common/changes/@rushstack/heft-web-rig/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..c7a28221017
--- /dev/null
+++ b/common/changes/@rushstack/heft-web-rig/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "patch",
+      "packageName": "@rushstack/heft-web-rig"
+    }
+  ],
+  "packageName": "@rushstack/heft-web-rig",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/common/changes/@rushstack/heft/config-file-null_2025-04-16-01-15.json b/common/changes/@rushstack/heft/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..c0ebb0781b5
--- /dev/null
+++ b/common/changes/@rushstack/heft/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "patch",
+      "packageName": "@rushstack/heft"
+    }
+  ],
+  "packageName": "@rushstack/heft",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/common/changes/@rushstack/lockfile-explorer/config-file-null_2025-04-16-01-15.json b/common/changes/@rushstack/lockfile-explorer/config-file-null_2025-04-16-01-15.json
new file mode 100644
index 00000000000..fb52e6fb85e
--- /dev/null
+++ b/common/changes/@rushstack/lockfile-explorer/config-file-null_2025-04-16-01-15.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Update documentation for `extends`",
+      "type": "patch",
+      "packageName": "@rushstack/lockfile-explorer"
+    }
+  ],
+  "packageName": "@rushstack/lockfile-explorer",
+  "email": "dmichon-msft@users.noreply.github.com"
+}
\ No newline at end of file
diff --git a/heft-plugins/heft-api-extractor-plugin/src/schemas/api-extractor-task.schema.json b/heft-plugins/heft-api-extractor-plugin/src/schemas/api-extractor-task.schema.json
index bfaec0ab038..9710f292181 100644
--- a/heft-plugins/heft-api-extractor-plugin/src/schemas/api-extractor-task.schema.json
+++ b/heft-plugins/heft-api-extractor-plugin/src/schemas/api-extractor-task.schema.json
@@ -13,7 +13,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },
 
diff --git a/heft-plugins/heft-sass-plugin/src/schemas/heft-sass-plugin.schema.json b/heft-plugins/heft-sass-plugin/src/schemas/heft-sass-plugin.schema.json
index 252929c3139..0ff5b533c91 100644
--- a/heft-plugins/heft-sass-plugin/src/schemas/heft-sass-plugin.schema.json
+++ b/heft-plugins/heft-sass-plugin/src/schemas/heft-sass-plugin.schema.json
@@ -13,7 +13,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },
 
diff --git a/heft-plugins/heft-sass-plugin/src/templates/sass.json b/heft-plugins/heft-sass-plugin/src/templates/sass.json
index 241166bb89f..88b2b1a7120 100644
--- a/heft-plugins/heft-sass-plugin/src/templates/sass.json
+++ b/heft-plugins/heft-sass-plugin/src/templates/sass.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/serve-command.json",
 
diff --git a/heft-plugins/heft-typescript-plugin/src/schemas/typescript.schema.json b/heft-plugins/heft-typescript-plugin/src/schemas/typescript.schema.json
index ff66372aa51..d42ff1f0476 100644
--- a/heft-plugins/heft-typescript-plugin/src/schemas/typescript.schema.json
+++ b/heft-plugins/heft-typescript-plugin/src/schemas/typescript.schema.json
@@ -13,7 +13,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from.  This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },
 
diff --git a/libraries/heft-config-file/src/ConfigurationFileBase.ts b/libraries/heft-config-file/src/ConfigurationFileBase.ts
index bd17fb686ce..91dec3f5095 100644
--- a/libraries/heft-config-file/src/ConfigurationFileBase.ts
+++ b/libraries/heft-config-file/src/ConfigurationFileBase.ts
@@ -16,6 +16,8 @@ interface IConfigurationJson {
  * @beta
  *
  * The set of possible mechanisms for merging properties from parent configuration files.
+ * If a child configuration file sets a property value to `null`, that will always delete the value
+ * specified in the parent configuration file, regardless of the inheritance type.
  */
 const InheritanceType = {
   /**
@@ -251,6 +253,7 @@ export interface ICustomPropertyInheritance<TObject> extends IPropertyInheritanc
    * Provides a custom inheritance function. This function takes two arguments: the first is the
    * child file's object, and the second is the parent file's object. The function should return
    * the resulting combined object.
+   * This function will not be invoked if the current value is `null`, the property will simply be deleted.
    */
   inheritanceFunction: PropertyInheritanceCustomFunction<TObject>;
 }
@@ -1085,7 +1088,15 @@ export abstract class ConfigurationFileBase<TConfigurationFile, TExtraOptions ex
         newValue = parentPropertyValue;
       };
 
-      if (propertyValue !== undefined && parentPropertyValue === undefined) {
+      if (propertyValue === null) {
+        if (parentPropertyValue !== undefined) {
+          resultAnnotation.originalValues[propertyName] = this.getPropertyOriginalValue({
+            parentObject: parentObject,
+            propertyName: propertyName
+          });
+        }
+        newValue = undefined;
+      } else if (propertyValue !== undefined && parentPropertyValue === undefined) {
         usePropertyValue();
       } else if (parentPropertyValue !== undefined && propertyValue === undefined) {
         useParentPropertyValue();
@@ -1207,7 +1218,10 @@ export abstract class ConfigurationFileBase<TConfigurationFile, TExtraOptions ex
         }
       }
 
-      result[propertyName] = newValue;
+      if (newValue !== undefined) {
+        // Don't attach the key for undefined values so that they don't enumerate.
+        result[propertyName] = newValue;
+      }
     }
 
     return result;
diff --git a/libraries/heft-config-file/src/test/ConfigurationFile.test.ts b/libraries/heft-config-file/src/test/ConfigurationFile.test.ts
index 117be997012..9b519beab09 100644
--- a/libraries/heft-config-file/src/test/ConfigurationFile.test.ts
+++ b/libraries/heft-config-file/src/test/ConfigurationFile.test.ts
@@ -251,6 +251,7 @@ describe('ConfigurationFile', () => {
       things: string[];
       thingsObj: { A: { B: string }; D: { E: string } };
       booleanProp: boolean;
+      stringProp?: string;
     }
 
     it('Correctly loads the config file', () => {
@@ -266,7 +267,8 @@ describe('ConfigurationFile', () => {
       const expectedConfigFile: ISimpleConfigFile = {
         things: ['A', 'B', 'C'],
         thingsObj: { A: { B: 'C' }, D: { E: 'F' } },
-        booleanProp: true
+        booleanProp: true,
+        stringProp: 'someValue'
       };
       expect(JSON.stringify(loadedConfigFile)).toEqual(JSON.stringify(expectedConfigFile));
     });
@@ -284,7 +286,8 @@ describe('ConfigurationFile', () => {
       const expectedConfigFile: ISimpleConfigFile = {
         things: ['A', 'B', 'C'],
         thingsObj: { A: { B: 'C' }, D: { E: 'F' } },
-        booleanProp: true
+        booleanProp: true,
+        stringProp: 'someValue'
       };
       expect(JSON.stringify(loadedConfigFile)).toEqual(JSON.stringify(expectedConfigFile));
     });
@@ -317,7 +320,8 @@ describe('ConfigurationFile', () => {
           A: { B: nodeJsPath.resolve(__dirname, configFileFolderName, 'C') },
           D: { E: nodeJsPath.resolve(__dirname, configFileFolderName, 'F') }
         },
-        booleanProp: true
+        booleanProp: true,
+        stringProp: 'someValue'
       };
       expect(JSON.stringify(loadedConfigFile)).toEqual(JSON.stringify(expectedConfigFile));
     });
@@ -350,7 +354,8 @@ describe('ConfigurationFile', () => {
           A: { B: nodeJsPath.resolve(__dirname, configFileFolderName, 'C') },
           D: { E: nodeJsPath.resolve(__dirname, configFileFolderName, 'F') }
         },
-        booleanProp: true
+        booleanProp: true,
+        stringProp: 'someValue'
       };
       expect(JSON.stringify(loadedConfigFile)).toEqual(JSON.stringify(expectedConfigFile));
     });
@@ -383,7 +388,8 @@ describe('ConfigurationFile', () => {
           A: { B: nodeJsPath.resolve(projectRoot, 'C') },
           D: { E: nodeJsPath.resolve(projectRoot, 'F') }
         },
-        booleanProp: true
+        booleanProp: true,
+        stringProp: 'someValue'
       };
       expect(JSON.stringify(loadedConfigFile)).toEqual(JSON.stringify(expectedConfigFile));
     });
@@ -416,7 +422,8 @@ describe('ConfigurationFile', () => {
           A: { B: nodeJsPath.resolve(projectRoot, 'C') },
           D: { E: nodeJsPath.resolve(projectRoot, 'F') }
         },
-        booleanProp: true
+        booleanProp: true,
+        stringProp: 'someValue'
       };
       expect(JSON.stringify(loadedConfigFile)).toEqual(JSON.stringify(expectedConfigFile));
     });
@@ -435,6 +442,7 @@ describe('ConfigurationFile', () => {
       things: string[];
       thingsObj: { A: { B?: string; D?: string }; D?: { E: string }; F?: { G: string } };
       booleanProp: boolean;
+      stringProp?: string;
     }
 
     it('Correctly loads the config file with default config meta', () => {
diff --git a/libraries/heft-config-file/src/test/simpleConfigFile/simpleConfigFile.json b/libraries/heft-config-file/src/test/simpleConfigFile/simpleConfigFile.json
index 37dfdc3f199..4db0a32d630 100644
--- a/libraries/heft-config-file/src/test/simpleConfigFile/simpleConfigFile.json
+++ b/libraries/heft-config-file/src/test/simpleConfigFile/simpleConfigFile.json
@@ -9,5 +9,7 @@
       "E": "F"
     }
   },
-  "booleanProp": true
+  "booleanProp": true,
+
+  "stringProp": "someValue"
 }
diff --git a/libraries/heft-config-file/src/test/simpleConfigFile/simpleConfigFile.schema.json b/libraries/heft-config-file/src/test/simpleConfigFile/simpleConfigFile.schema.json
index 3d118ed35a1..0c2c53a91b8 100644
--- a/libraries/heft-config-file/src/test/simpleConfigFile/simpleConfigFile.schema.json
+++ b/libraries/heft-config-file/src/test/simpleConfigFile/simpleConfigFile.schema.json
@@ -24,6 +24,10 @@
 
     "booleanProp": {
       "type": "boolean"
+    },
+
+    "stringProp": {
+      "type": "string"
     }
   }
 }
diff --git a/libraries/heft-config-file/src/test/simpleConfigFileWithExtends/simpleConfigFileWithExtends.json b/libraries/heft-config-file/src/test/simpleConfigFileWithExtends/simpleConfigFileWithExtends.json
index ce8b0e3e2b4..5a4b4c5ce9e 100644
--- a/libraries/heft-config-file/src/test/simpleConfigFileWithExtends/simpleConfigFileWithExtends.json
+++ b/libraries/heft-config-file/src/test/simpleConfigFileWithExtends/simpleConfigFileWithExtends.json
@@ -13,5 +13,7 @@
     }
   },
 
-  "booleanProp": false
+  "booleanProp": false,
+
+  "stringProp": null
 }
diff --git a/libraries/rush-lib/assets/website-only/rush-project.json b/libraries/rush-lib/assets/website-only/rush-project.json
index 819dd322050..1347fb59eea 100644
--- a/libraries/rush-lib/assets/website-only/rush-project.json
+++ b/libraries/rush-lib/assets/website-only/rush-project.json
@@ -8,6 +8,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "my-rig/profiles/default/config/rush-project.json",
 
diff --git a/libraries/rush-lib/src/schemas/pnpm-config.schema.json b/libraries/rush-lib/src/schemas/pnpm-config.schema.json
index 6ab70eb2667..a5256c98228 100644
--- a/libraries/rush-lib/src/schemas/pnpm-config.schema.json
+++ b/libraries/rush-lib/src/schemas/pnpm-config.schema.json
@@ -11,7 +11,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from. This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from. This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },
 
diff --git a/libraries/rush-lib/src/schemas/rush-project.schema.json b/libraries/rush-lib/src/schemas/rush-project.schema.json
index 50bec9241da..6e686581253 100644
--- a/libraries/rush-lib/src/schemas/rush-project.schema.json
+++ b/libraries/rush-lib/src/schemas/rush-project.schema.json
@@ -12,7 +12,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from. This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from. This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },
 
diff --git a/rigs/heft-node-rig/profiles/default/config/heft.json b/rigs/heft-node-rig/profiles/default/config/heft.json
index cc2763f149a..922aed1cd6b 100644
--- a/rigs/heft-node-rig/profiles/default/config/heft.json
+++ b/rigs/heft-node-rig/profiles/default/config/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/heft.json",
 
diff --git a/rigs/heft-node-rig/profiles/default/config/typescript.json b/rigs/heft-node-rig/profiles/default/config/typescript.json
index 50ab4719c5d..ac7c00881b3 100644
--- a/rigs/heft-node-rig/profiles/default/config/typescript.json
+++ b/rigs/heft-node-rig/profiles/default/config/typescript.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/typescript.json",
 
diff --git a/rigs/heft-web-rig/profiles/app/config/heft.json b/rigs/heft-web-rig/profiles/app/config/heft.json
index bdf1a762f11..9830c15f31c 100644
--- a/rigs/heft-web-rig/profiles/app/config/heft.json
+++ b/rigs/heft-web-rig/profiles/app/config/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/heft.json",
 
diff --git a/rigs/heft-web-rig/profiles/app/config/sass.json b/rigs/heft-web-rig/profiles/app/config/sass.json
index 2aabb61e19d..f6fe4ffe9c5 100644
--- a/rigs/heft-web-rig/profiles/app/config/sass.json
+++ b/rigs/heft-web-rig/profiles/app/config/sass.json
@@ -10,6 +10,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/serve-command.json",
 
diff --git a/rigs/heft-web-rig/profiles/app/config/typescript.json b/rigs/heft-web-rig/profiles/app/config/typescript.json
index 123e40a0d2f..91a9bc59c3b 100644
--- a/rigs/heft-web-rig/profiles/app/config/typescript.json
+++ b/rigs/heft-web-rig/profiles/app/config/typescript.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/typescript.json",
 
diff --git a/rigs/heft-web-rig/profiles/library/config/api-extractor-task.json b/rigs/heft-web-rig/profiles/library/config/api-extractor-task.json
index 46fdc5f876a..a051e971819 100644
--- a/rigs/heft-web-rig/profiles/library/config/api-extractor-task.json
+++ b/rigs/heft-web-rig/profiles/library/config/api-extractor-task.json
@@ -10,6 +10,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/api-extractor-task.json",
 
diff --git a/rigs/heft-web-rig/profiles/library/config/heft.json b/rigs/heft-web-rig/profiles/library/config/heft.json
index bdf1a762f11..9830c15f31c 100644
--- a/rigs/heft-web-rig/profiles/library/config/heft.json
+++ b/rigs/heft-web-rig/profiles/library/config/heft.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/heft.json",
 
diff --git a/rigs/heft-web-rig/profiles/library/config/sass.json b/rigs/heft-web-rig/profiles/library/config/sass.json
index 2aabb61e19d..f6fe4ffe9c5 100644
--- a/rigs/heft-web-rig/profiles/library/config/sass.json
+++ b/rigs/heft-web-rig/profiles/library/config/sass.json
@@ -10,6 +10,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/serve-command.json",
 
diff --git a/rigs/heft-web-rig/profiles/library/config/typescript.json b/rigs/heft-web-rig/profiles/library/config/typescript.json
index 123e40a0d2f..91a9bc59c3b 100644
--- a/rigs/heft-web-rig/profiles/library/config/typescript.json
+++ b/rigs/heft-web-rig/profiles/library/config/typescript.json
@@ -7,6 +7,8 @@
   /**
    * Optionally specifies another JSON config file that this file extends from. This provides a way for standard
    * settings to be shared across multiple projects.
+   *
+   * To delete an inherited setting, set it to `null` in this file.
    */
   // "extends": "base-project/config/typescript.json",
 
diff --git a/rush-plugins/rush-serve-plugin/src/schemas/rush-project-serve.schema.json b/rush-plugins/rush-serve-plugin/src/schemas/rush-project-serve.schema.json
index af1dad75e00..dde1549b4a6 100644
--- a/rush-plugins/rush-serve-plugin/src/schemas/rush-project-serve.schema.json
+++ b/rush-plugins/rush-serve-plugin/src/schemas/rush-project-serve.schema.json
@@ -12,7 +12,7 @@
     },
 
     "extends": {
-      "description": "Optionally specifies another JSON config file that this file extends from. This provides a way for standard settings to be shared across multiple projects.",
+      "description": "Optionally specifies another JSON config file that this file extends from. This provides a way for standard settings to be shared across multiple projects. To delete an inherited setting, set it to `null` in this file.",
       "type": "string"
     },