The TF Site Team is happy to help when a seller requests it but if we had to take administrative action for each and every thread with an item that sells, we'd have a MUCH larger job for our small team of dedicated community volunteers.
If it's your ad and the item sells, please feel free to post SOLD as the final post. If you really need the thread frozen and/or relabeled, just report your last post with the request in the dialog box. We'll get a notification in our inbox and one of the TF Site Team will get on it.