Scenario: The primary server participating in a database mirroring configuration has gone offline. It has been decided that there not enough time to troubleshoot bringing the primary server online and the mirror server will now assume the responsibility of the primary server.
Use this command to manually remove database mirroring and make the secondary database available for use.
Note: this will break mirroring, essentially creating 2 independent databases.
ALTER DATABASE [database_name] SET PARTNER OFF
RESTORE DATABASE [database_name] WITH RECOVERY