Edit Account in WHM
From Lunarpages Web Hosting Wiki
This is how you would delete an account using Web Host Manager (WHM). Editing an account in WHM is handy when you need to change account features on your plans created under your dedicated hosting server space.
The first thing you would need to do is login to WHM. From the front page, click on "Account Functions" and then "Modify an Account". You will then go to the Modify an Account page.
Click on the domain or user name for the account you wish to modify. Now, click on the "Modify" button. Now you can alter your account settings for this domain.
You can change the domain name on this account, change the domain's cPanel theme (if available), or the user name. You can also edit the account "max" limits. Once you are done, hit the "Save" button, and you are done.