• There is no disabled users in a database. There may be users with no permissions or with permissions explicitly denied, but you can't disable a database user, you disable a login. Just to make sure we are on the same page I will define user and login:

      Login - an object that has permission to connect to the SQL Server and may have server level permission, but may or may not have access to a database or databases

      User - an object that is contained within a database that has permissions within the database and maps to Login.

        As dbo within a database you have the permissions to Alter/Drop/Create users within the database, but not to alter logins.