Start by rolling out an update for a user to leave a group chat and end a chat ( why roll out a product, without this simple feature).
We’ve listened and the ability to leave a chat will soon be released! To access it you will simply click the “…” overflow menu from the left rail, on the chat you wish to leave. A fly-out will appear allowing you to either Favorite, Mute, Hide, or Leave the chat.
Look for this early in the new calendar year! -Warren