Fix Orphan User 

EXEC sp_change_users_login 'auto_fix', 'prod1'

Later versions of SQL like this better:

EXEC sp_change_users_login 'auto_fix', 'prod1', NULL, 'prod1'


Steps to Drop an Orphan SQL Server User when it owns a Schema or Role

https://www.mssqltips.com/sqlservertip/2620/steps-to-drop-an-orphan-sql-server-user-when-it-owns-a-schema-or-role/