The trashcan is a holding area where you can move any of your works that you do not wish to be shown on the gallery. You can save it there and it is visible to only you until you either decide to put it back on the gallery or until you click on "Purge Trash" button.

Purging trash will delete your works entirely from the site and you will have to resubmit from scratch if you want it back on the gallery again. There is a 30 day waiting period once you put something in the trash before you can completely delete it.