Steve Jones uses dbatools to fix orphaned users:
One of the common issues that I would run into with refreshing development and test environments are the orphaned users. These are accounts that typically exist in production, but not in development. The logins and users are different in these environments, and often there isn’t a login on the development instance. This creates an orphaned user: one that exists in the database, but has no instance level mapping.
Cleaning up these users isn’t that hard, often with a removal of the user, mapping to a different login, or repairing this user by adding back the server login. These aren’t difficult tasks, but the logic to write a script to quickly fix this, especially in a DR situation, may not be handy.
Read on to see how easy dbatools makes this.