1. Stop the SQL Server database engine
2. Detach the database from the Blackbaud Management Console
3. Restart the SQL Server database engine

If still unable to detach the database, then detach all other databases listed in the Blackbaud Management Console, browse to the Setting.XML file, which resides in the [path]\Management Console\Bin folder on the server. Close the Blackbaud Management Console, rename this file, then reopen the Blackbaud Management Console. If the database still appears, follow steps 1 to 3 above again.