how to disable user registration

As the title says..how do I disable the registration? I only want specific people to be allowed to add content to the wiki.

Admin > Users > Login Settings: disable "Users can register"

keep getting this error when trying to save it:

Warning: include_once(Auth/Auth.php) function.include-once: failed to open stream: No such file or directory in /home/.mima/pazrt/pazrt.com/wiki/users/auth/ldap/auth.php on line 15

Warning: include_once() function.include: Failed opening 'Auth/Auth.php' for inclusion (include_path='/home/.mima/pazrt/pazrt.com/wiki/util/pear/:/home/.mima/pazrt/pazrt.com/wiki/util//:.:/usr/local/php5/lib/php:/usr/local/lib/php') in /home/.mima/pazrt/pazrt.com/wiki/users/auth/ldap/auth.php on line 15

this has been fixed by manually changing the table in mysql.