Try sending an email to:
fraternalnews-unsubscribe@yahoogroups.com and that should take care of it. Make sure you're sending the email from the account that is subscribed to the group. I've worked with other YahooGroups and it may take a day or two, but that should work!
You can also email the owner of the group at:
fraternalnews-owner@yahoogroups.com