How to remove one record from a list in a data type?

I have a data type “Vendor”. I have another Data Type “User”. In the “Vendor” data type I have a list of “Users”.

So how do I remove/delete a user in the list. I don’t want to completely delete the user I just want to remove the relationship. The workflow options are confusing me on which is the proper one to use and how to write the workflow.

Use a filter where the User <> the User to be deleted.