1. Login to your server WHM.
2. Search for “Modify an Account” from the left list and you will be redirected to a page contains all accounts on your server, choose the account that you would like to modify as you see in the following screenshot:
3.Click on the account that you want to modify as you see in the following screenshot:
4. Modify the username through the available options and then save changes as you see in the following screenshot:
