sp_revokedbaccess (Transact-SQL)
Applies to: 
SQL Server
Removes a database user from the current database.
Important
This feature will be removed in a future version of SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature. Use DROP USER instead.
Transact-SQL syntax conventions
Syntax
sp_revokedbaccess [ @name_in_db = ] N'name_in_db'
[ ; ]
Arguments
[ @name_in_db = ] N'name_in_db'
The name of the database user to be removed. @name_in_db is sysname, with no default. @name_in_db can be the name of a server login, a Windows login, or a Windows group, and must exist in the current database. When you specify a Windows login or Windows group, specify the name by which it's known in the database.
Return code values
0 (success) or 1 (failure).
Remarks
When the database user is removed, the permissions and aliases that depend on the user are also removed.
sp_revokedbaccess can remove only database users from the current database. Before removing a database user that owns objects in the current database, you must either transfer ownership of the objects or drop them from the database. For more information, see ALTER AUTHORIZATION.
sp_revokedbaccess can't be executed within a user-defined transaction.
Permissions
Requires ALTER ANY USER permission on the database.
Examples
The following example removes the database user mapped to Edmonds\LolanSo from the current database.
EXEC sp_revokedbaccess 'Edmonds\LolanSo';
GO