The account belongs to no single world, it is an account on tribal wars itself. You must delete the account itself to use the same e-mail to make a new account with a new name, or just use a different email and make a new account, and wrong area.
To completely delete an account after you have been successfully deleted on each world go to http://www.tribalwars.net/account_delete.php this will free up the email address to use it with another name.