add sample codes for Auth.deleteUserAttributes in JS

docs/guides/authentication/fragments/js/managing-user-attributes.md

@@ -56,6 +56,15 @@ async function updateUser() {
 }
 ```
 
+You can also use the `deleteUserAttributes` method of the __Auth__ class to delete user attributes:
+
+```js
+async function updateUser() {
+  const user = await Auth.currentAuthenticatedUser();
+  await Auth.deleteUserAttributes(user, ['address']);
+}
+```
+
 ### Reading user attributes
 
 To read user attributes, you can use the `currentAuthenticatedUser` method of the Auth class:
@@ -107,4 +116,15 @@ async function updateUser() {
     'custom:favorite_ice_cream': 'vanilla'
   });
 }
+```
+
+You can also use the `deleteUserAttributes` method of the __Auth__ class to delete custom user attributes:
+
+```js
+async function updateUser() {
+  const user = await Auth.currentAuthenticatedUser();
+  await Auth.deleteUserAttributes(user, [
+    'custom:favorite_ice_cream'
+  ]);
+}
 ```

docs/lib/auth/fragments/js/manageusers.md

@@ -161,6 +161,17 @@ let result = await Auth.updateUserAttributes(user, {
 console.log(result); // SUCCESS
 ```
 
+You can delete user attributes:
+
+```javascript
+let user = await Auth.currentAuthenticatedUser();
+
+let result = await Auth.deleteUserAttributes(user, [
+    'family_name'
+]);
+console.log(result); // SUCCESS
+```
+
 > You can find a <a href="https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-settings-attributes.html#cognito-user-pools-standard-attributes" target="_blank">list of all custom attributes here</a>.
 
 If you change the email address, the user will receive a confirmation code. In your app, you can confirm the verification code: