One of the best things PG ever said about HN is that comments "should be written in the spirit of colleagues cooperating in good faith to figure out the truth about something". I intend to add that to the site guidelines.
Please re-read what you post and, if doesn't have this quality, edit it until it does. If, after editing, there is nothing left, you should have no trouble deleting it (or just not posting). In my experience, this approach works—when one remembers to take it.