How do I remove a message from the group message board?
Resolution
Only the group commissioner, the person who created the group can remove a group message.
If you are a group commissioner, open the message. You will see a delete button below it.
If you are not a group commissioner and you want your message deleted, please contact the commissioner directly and request that they remove it. The decision is theirs, and Yahoo! will not arbitrate in the affairs of private groups.