Do you want to delete your thread here?
I doubt that you can do that. In an other forum software that I have used, W-Agora (a free and open-source forum software), you can delete the header post (the first post) of a thread, if you are the one who posted that thread and thus its header post. But these forums use vBulletin (a commercial/payware forum software), and so I do not know if anyone but an administrator can delete posts.
The best way to "delete" it, as far as I know, is to replace the post's content with a message indication that you deleted its contents (such as "Deleted.").
Regards.