SQL Server cannot drop the user's workaround because the selected user owns the object _mssql

Phenomenon:
restore the previously backed up database to the current SQL database and now delete the user from the database, but the result is that the selected user has the object, so the user cannot be dropped
Solution:

1. Open Enterprise Manager, expand the server, right click on the local service, properties :

To open the SQL Server Properties (configuration) window
2. Select General window
Select the Server Settings window, which will allow the system directory to be directly modified to select, OK.
4. Expand the database, see the Database system table sysusers, right-- open the table -- return all rows :

5. Select the user in the database to delete, find the related row, right-click Delete :


Choice is,
finally , return to the second step to allow the system directory to be directly modified before the hook to remove