How to Leave a Group Chat on Apple Messages

Method 1 of 2:

Open the Messages app.
Tap the chat you wish to leave.
Tap ⓘ. It's in the upper-right corner of the screen.
Check the number of chat participants. If there are fewer than four, you will have to add a contact or two in order to leave.
Tap + Add Contact. Add contacts until there are four participants in the chat.
Tap Leave this Conversation. You've now left the group chat on iMessage.

Method 2 of 2:

Open the Messages application.
Click on the group chat you wish to leave. The conversations are listed on the left side of the of the window.
Click on Details. It's a blue link in the upper right of the messages window.
Check the number of chat participants. If there are fewer than four, you will have to add a contact or two in order to leave.
Click on Add Member. Add contacts until there are four participants in the chat.
Click on Leave this Conversation. You've now left the group chat on iMessage.

For users of Apple products, the convenience and immediacy of the Messages app (or 'iMessage' as it used to be known) can't be overstated. However, the constant alerts from a group chat, which Messages considers a chat with four or more...