You do know it is a Saturday and your other account that asked the same question did it at 2 am eastern time this morning. You actually did get a response in that other thread.
If it is just a few posts, you ask the mods in the forum in question to do it for you. For LLSNL, we'll generally do it if it is a one time request and there aren't a lot of posts.
If the problem is bigger, you can email Mat Sklansky at
mat@twoplustwo.com Mat will eventually get back to you, but it may be a week or so before he does it.
Mat recently commented on this type of request with someone who was worried about a work promotion. His response was that if the reasons are good, 2+2 will offer to allow you to register a new account and delete the old one. Unless there are just a few posts, 2+2 won't delete the posts. The rationale is that nothing is ever deleted from the internet. Just because it is deleted on 2+2 doesn't mean that it isn't archived somewhere else. If you are the work promotion person, it will be fairly easy for your company to find them again. I can find posts with Google I made on Yahoo 15 years ago that don't don't exist on the website any longer.
For the general audience, the lesson is that everything you post here is public. Just as you can't erase from everyone's mind you drunkenly abusing a bartender for cutting you off from more drinks, you can't erase drunken spew from the internet.