Just noticed this script, which I think many people might not be aware of. Ok it is not something you would need every day, but in some cases you may find yourself in need of it...
In <OWB_HOME>/owb102/owb/misc you find 3 scripts:
The only one you care about is the SQL one... Now use this only (like the script says) when you cannot get to the control center anymore. Say the database got deleted (runtime that is), but your location in the client still says it is registered. Since you cannot go to the control center an unregister, you need to do something. That is where unregister_location.sql comes in...
Before running it do read the script, it nicely tells you which user to use it in (Repository Owner).
Oh and for those of you new to 10.2, you should not declare this the default to unregistering a location... 10.2 has this capability in the Control Center Manager and you do not have to go to the browser... So it is already quite a bit simpler. Remember just use this one when you are really stuck.