Use sp_revokelogin or revoke to revoke permissions that were granted with sp_grantlogin.
Use:
-
The sp_revokelogin command when Adaptive Server is running
under Integrated Security mode or under Mixed mode, and the connection is
Named Pipes.
-
The revoke command when Adaptive Server is running under
Standard mode or under Mixed mode, and the connection is other than Named
Pipe.
This command line revokes all permissions from the Windows group named Administrators:
sp_revokelogin Administrators