Usernames are not listed there, when I’m looking for PM from particular user I go through advanced search:
Well at least we know that you changed your mind and deleted the post. Usually some people have already reacted to your message by that time, so we at least know that the topic is missing few bits of discussion.
Anyway deleting the post should be needed only if the content is against the rules, not because you have changed your mind. Having people react to your post and then removing it is against netiquette. Again this is public discussion board. In history removing the post wasn’t even technically possible (remember newsgroups?).