You may have an MBR associated with that group name. If that's the case,
you need to change that MBR so that it's under a different billing group.
Once that's done, you can probably delete the group.
select * from groups
delete from groups where groupid = n
Where n represents whatever ID is associated with the group name you
recognize, obtained from the first one-line script.
Josh
For more information about this list (including removal) go to:
http://www.iea-software.com/support/maillists/liststart