This guide was created with Microsoft SQL Server 2008 in mind, but should work for any version of SQL Server. It assumes the databases are in a synchronous mirroring configuration with no witness server and that you are using an account with Admin access to both servers and databases.
In this guide the database is called Database9.
You may have restored a database with the (RESTORE WITH NORECOVERY) option (see Restore a mirrored database) or failed a database over to its mirrored copy (see Fail a database over to a mirror server in the event of a DR Test) and need to delete the now mirrored copy of the database.
You can remove a database mirror with the help of the article Remove a database mirror.
Then to remove the mirrored copy:
1. Execute the following code against the master database:
RESTORE DATABASE Database9 WITH RECOVERY
2. Right-click on the database and select Delete.
3. Ensure Close existing connections is ticked and press OK.
If you are completely removing a database from the network you will need to delete it from both the Principal and Mirror servers.