While you can have your threads removed by the LttD moderators and administrators, you want to investigate contacting Google and other notable search engines about having your posts removed from their servers. This suggestion is purely hypothetical, for I have never done so Myself, but it may be worth investigating if you have concerns about your security. Google and several other search engines sometimes maintain cached versions of pages that can survive long after the orgininal is gone from the web. I would imagine this is done for their more popularly searched results, but again, I am guessing here.
Perhaps that leans toward paranoia, but I thought you should know.