i created mothers and fathers group so that on mothers day and fathers day i could just send one greeting only. i later discovered people were receiving messages from group members. i deleted the group but it is still operating out there.
Deleting a group is not the same as deleting a group.
Have somebody from that group write something to that group.
The group will reappear in your chats and you can see who the group admin is.
Let the group admin know that you'd like him to delete the group.
He can find that option by tapping on the group title and scroll all the way down.