1. Login to Admin Console.
  2. From the Admin console dashboard, go to Users.
  3. In the user list, next to the user you want to rename, click Rename Edit .

    Or from the top-right of the user's account page, click more Settings >  Rename user.

  4. Change either of these names:
    • First name and Last name: Changes the user's default display name.
    • Primary email address: Changes the user's sign-in name and primary email address (if your organization uses Gmail). If your Google account has multiple domains, you can select another domain name from the list.

Note: Changing someone's primary email address changes the name they use to sign in to their Google Account. It also changes their primary email address. It can have other significant effects, too. Before continuing, see Impact of changing a username.

        5. Click Rename User.


It can take up to 10 minutes for a new primary email address to take full effect. It can take 24 hours if you change the user’s domain name. And it can take up to 3 days before the user can use Google Talk. For details, see Impact of changing a username.


Note:

A user can change their display name via Google+

  • You may find that a user name is not changing when you set it in the Admin console. If a user has a Google+ profile and changes their profile name, the new profile name shows in Google services—not the display name you set in the Admin console. If you don’t want users to change their own display names, you can prevent users from changing their Google+ profile names.

A user's name may not show up when they send email

  • When you change a user's name in the Admin console, the new name may not show up correctly when the user sends email. Tell users they can change their name in Gmail Settings.


For more information about rename a user, kindly visit: Rename a user