We generally don't like to delete posts and threads unless they way violate the rules.
Wew ould also prefer that members don't delete their posts and it ruins the continuity of the thread.
If you would like a thread closed because you have sold whatever youa re selling, let a moderator know. Or as suggested, just edit it to put SOLD in the subject. It will fall off the front pages yet a thread that has your stuff SOLD with no complaints, it shows you are a good seller.