No, its not possible to close it yourself. You need to get it closed by any of the mods. By the way you can edit it upto 8 hours from when you posted the thread or any post. - Digital -
was the Delet it yourself removed ? i know a while ago you could delete your own thread IF it was done withing 30 minutes of it's creation.
I dont think that you can close them. Asking the mods to "lock" them should help. You can also ask them to shift to a relevant place if needed, but closing ain't possible I guess