sp_validatelogins (Transact-SQL)
SQL Server 2012
Reports information about Windows users and groups that are mapped to SQL Server principals but no longer exist in the Windows environment.
If the orphaned server-level principal owns a database user, the database user must be removed before the orphaned server principal can be removed. To remove a database user, use DROP USER. If the server-level principal owns securables in the database, ownership of the securables must be transferred or they must be dropped. To transfer ownership of database securables, use ALTER AUTHORIZATION.
To remove mappings to Windows users and groups that no longer exist, use DROP LOGIN.
