You can't delete a thread.
Option 1: If you sober up enough in the first hour, you can edit your post. Edit may mean you just hit the edit key and then backspace out the entire posts, replacing it with a polite NEVERMIND.
Option 2: If more than an hour, hit the
symbol, and report the post to the mods and ask them to fix your gaffe. Be polite, and if they think it is appropriate, they may save you from being flamed.