You can't remove them. If you regret your question quick enough, you can change it, but that's only for about 10 minutes. It'll be all right. Everyone should ask at least one awkward question. It's good for the soul ;)
--try clicking the report as button maybe ask a couple of trusted connections to report it as well. The mods just might remove it. I don't think there's any real harm in having a question or answer reported, especially if it's just one.
You can't. It is impossible for you to do so, unless you hack into a mods account, and delete it yourself. Only a mod can do it. And they will only delete the question if it goes against the guidelines.