If you log out incorrectly as "admin" or other user you must be waiting timeout session ( normally configured to 30 minutes ) to login again.
One of the admin utilities is to force logout to users ( when they loged out uncorrectly ), as a admin you might not do it

.
Actually there's no backdoor to logout admin user. The only unacceptable way to do it is resetting jboss server -> worst that waiting 30 minutes I think.
If it's a great inconvenient we'll think on some way to force logout admin user on next OpenKM release, tell us about you point of view.