Only admin can delete the group.  You also should ask the other members of the group if they still want the group going before just having it deleted.  Admin for the group can be handed on to someone else if they want the group to keep going.

Generaly speaking, you don't delete it. You pass the administration of the group to someone else and then leave the group. What the person that you handed it to and the other members in the group do with it once you've gone is up to them and no longer your problem.

you have to email Matthew or clay and get them to do it.