Here is what you have to do to delete a user account in Windows 7
Step 1. Click the Start button from the bottom left hand corner of the screen. Start button on your keyboard.
Step 2. Click Control Panel.
Step 3. Under User Accounts and Family Safety click Add or remove user accounts.
Step 4. Select the account you would like to delete.
Step 5. Click Delete the account.
Step 6. You will be asked if you would like to keep the files associated to the user account.
If you want to keep the files, click the Keep Files button.
All the files will be saved in a folder on the desktop, If you do not want to keep the files,
click the Delete Files button.
Step 7. A final warning will be displayed: Are you sure you want to delete USERNAME’s account?
Click Delete Account.