My view on it is unless you make a double post, a post in an incorrect thread or have it deleted by a moderator there isn't much of a reason to. A lot of times when people come in, get their advice and delete their thread or post I'll restore it because other people may benefit it. While I realize some people get super paranoid about someone stumbling across their post, it's really not such a bad problem to deny others the chance to get your insight or something. Personally I see it as selfish to remove things you've said like that, but it really depends on the individual situation. If the post didn't really add much I won't fuss over it.