If you want to completely remove OBM from Windows, after uninstalling the software from [Control Panel] -> [Add or Remove Programs], please do the followings:

Ensure that the OBM installation directory is deleted (sometimes not removed when Windows somehow holds some of the files)

Remove the C:\Documents and Settings\administrator\.obm\ folder (intentionally left undeleted, as important information of the user and backup sets, such as the encryption keys, are stored here)