Not sure. Updates are not always user friendly. I am not adverse to change, but it needs to be something that we can understand. I am fairly up on digital stuff, but sometimes the language is tough to deal with.I am "old guy" and not trained in computer stuff - so this is mostly my "WAG". I suspect "delete" may imply, to some, that it has been removed / gone / vanished - whereas "leave the conversation" probably implies that the text exchange still exists somewhere - but you can not see it and it no longer counts as one of your messages?