I am stuck in a group chat with SMS and can’t figure out how to leave. What can I do?

How to leave a group text

1. Go to the group text that you want to leave.
2. Tap the top of the conversation. 
3. Tap , then tap Leave this Conversation.

If you don't see the option to leave, it might mean one or more of the users isn't using a device with iMessage. You can't remove yourself from these group texts, but you can mute the conversation.

How to mute your messages

1. Go to the group text.
2. Tap the top of the conversation, then tap .
3. Turn on Hide Alerts.

You can also swipe left over the group text and tap Hide Alerts. When Hide Alerts is on, you'll find a crescent moon  next to the conversation.

Hide Alerts stops notifications for a specific group text, not your device. You'll still receive all other messages and notifications on your Lock screen. Learn more about managing your notifications.

I know, not exactly what you were looking for however muting that group would be the right option.

Axel F.