Closing your listing is required when an item has been sold or simply when it is no longer available. To close a listing, simply navigate to your topic and press the Close button, as seen in the following screenshot:
Option #1 - Just close.
This simply closes the topic which can be later opened by asking administrators/moderators.
Option #2 - Close + mark sold.
This option will remove the price, URL, mark the item as sold, and permanently close the listing.