You can hard-code what is displayed on the Member List by altering the URL. Normally, the URL to your Member List will look similar to this:
http://www.example.com/index.php/member/memberlist/
You can add another segment to the end of the URL to specify the Member Group and other options like so:
http://www.example.com/index.php/member/memberlist/1-screen_name-asc-10-10/
The parts of the segment (separated by dashes) in order are:
- group_id
- sort by
- order
- row count
- row limit
If you would like to use the standard member list but exclude a particular group, then you can set that in the Member Group Preferences.