Delete, as in no longer want that particular gift or ribbon to be given out? Or Delete, as in remove from the user that got it?
I am thinking that you want to know how to remove them totally. And I am no expert, but I do it like I add them, just delete them from my server (your FTP server, images/gifts or images/ribbon) and they are gone. But if any user has gotten or given that gift or ribbon, it will show a little red x so you will also have to delete them from their profile as well. I hope this helps, and that I am not totally wrong

Lisa