There's nothing to be achieved by deleting topics, and "restarting" onto a new thread is a bad idea, as it splits up the discussion. Just edit your first post when necessary. When there is not a more recent post, you are able to remove your own posts, but entire threads which contain others posts are not your "property". Sure, the first few posts in reply to yours may be outdated, but that's the way forums work (technically, it's possible to re-arrange posts to show the most recent first, personally, by ticking the "Show most recent posts at the top" box in Profile > Modify Profile > Look and Layout, though I can't personally recommend that, as generally the most important post in a thread is the first one).
Is there any particular reason to need a new thread when you can change the title any time (edit the first post and modify the title of that), can add polls (link at the top, presuming you created the thread), and can modify the first post to reflect the mod's current progress (should be self evident)?
