If you have a user account on your computer that is not being used, you can permanently remove it by deleting it.
The steps that you should follow will vary, depending on whether your computer is on a domain or a workgroup. To find out, see "To check if your computer is on a workgroup or domain" in What is the difference between a domain, a workgroup, and a homegroup?
Because your computer is on a domain, you can delete local user accounts from the computer, but you cannot delete user accounts from the domain. All files that were created under the user account will be deleted when you delete the account.
On the Users tab, under Users for this computer, click the user account name, and then click Remove.
In the User Accounts dialog box, click Yes, and then click OK.
When you delete a user account, you can choose whether you want to keep the files created under that account; however, e-mail messages and computer settings for the account will be deleted.
Click the account you want to delete, and then click Delete the account.
Decide if you want to keep or delete the files created under the account by clicking Keep Files or Delete Files.
Click Delete Account.