Dropping a remote login deletes the remote login ID from the sysremotelogins table and prevents that user from accessing the remote server through his or her local server.
sp_dropremotelogin remoteserver [, loginame [, remotename]]
where
For example, to drop the remote user chris from the remote server ACCOUNTS who was mapped to the local user salesmgr:
sp_dropremotelogin accounts, salesmgr, chris
For more information about sp_dropremotelogin, see the Microsoft SQL Server Transact-SQL Reference.