Log in to your DirectAdmin Account.
In the E-mail Manager section, click on the E-mail Accounts Icon or type E-mail Accounts in the navigation filter box. The option will appear. Click on it.
Under Account, you can see your email address along with the Plus icon on the right-hand side.
Click on the Plus icon and then on the Change Password/Username option.
In the Username field, modify/rename your email username.
Your email address will be renamed successfully.