How to permanently delete group messages
I have two different family group messages. One has 3 people, one has 4. I want to stop and delete the 3 group and only have 4 group, but anytime I delete the group name with 3 persons, and one person from group writes to anyone in group, the old 3 group comes back. Also with this problem, any of us can write in one group and the message appears to others in different group names different times, even if on my side I am writing inside one specific group.
This sounds confusing, but what it is is frustrating, as others say they have to keep jumping from group to group to get any messages. Something is keeping all this in memory someplace in messages on desktop, or messages on iphone.
On iPhone6, iOS 9.1, in SETTINGS/MESSAGES, I've tried turning off Text Message Forwarding, deleting all the "groups" but the one with 4 in it, and turn back on, and same thing happens.
Going thru a long list of individual messages inside a group and deleting each one will take FOREVER, since I have chose to "keep forever" in settings 😟. Is there any other way to fix this problem and in some fast way?
iPhone 6, iOS 9.1