Instructions
Turn on your Xbox 360.
Scroll to the "My Xbox" menu.
Navigate to the "System Settings" panel, then press "A" on your controller to select it.
Scroll to "Memory," and press "A" to select it.
Select the storage device on which the Gamertag profile is located, then press "A."
Press "A" on the "Gamer Profiles" option.
Scroll to the Gamertag profile you want to delete, and then press "A' to select it.
Select the "Delete" option, and press "A."
Scroll to "Delete Profile Only," then press "A."