In June I marked a FS ad as Sold/Closed thinking it would disappear from site. The ad is now marked Sold but the original words and photos are still viewable. How do I remove the ad completely?

 

It stays up forever.

Once marked sold, the thread is closed and no comments can be made to the post.

It stays up to protect members from scams. For example, you sell something in the ad and a month later the seller claims you did something wrong/untrustworthy, the post is there as evidence of the sale and such.