Users should be able to enable/disable their accounts by themselves. Once it's disabled they should be redirected to a specific page where they can only browse their account's status but they should not be able to browse the website (feeds, user profiles etc).
Also it would be very good if you can add a text box for account disabling or deletion reason. It's very important for owners to get to know the reason why they wants to disable or delete their accounts.
I think we called this "users tool"