1. Only mods can close a thread. MR policy in general is not to close threads except in special circumstances, so even if you ask, it most likely will remain open.
2. Again, only a mod can delete a thread and it most likely won't happen.
3. You can't delete your own post, but you can edit it at any time, effectively deleting any meaningful content, or else fixing the bits you screwed up. As I'm doing here!
You can request a post be deleted by reporting it.
Hope this helps. Welcome to MR!