My board is probably being hacked as I can't delete a particular user who is spamming. The user use a name "Guest" but when I hover my mouse over, the URL points to http://www.myforum.com/forum/member//
Clicking it points to a page that says "The forum you selected does not exist."
Also The requested user does not exist when I tried to search via Manage users in the admin Control Panel too.
How do I delete this user and all this posts?