Suppose I am composing a reply to a message and part way through I change my mind and want to delete it. How do I do it? I don't see any "delete" button.
There is not an 'abort' or 'cancel' button but as long as you do not hit post it will not get posted.
So if you navigate away from the page by clicking on a link on the page or just hitting the back button the post will not get posted.