If you've deleted them on Xbox Live they should be removed here automatically, since we don't host the screenshots ourselves and they are served directly from Xbox. There might be some delay before it happens, however.
Can you send me a link to one of the deleted screenshots still showing up? (In Chrome, do right click -> Copy Image Address on the full image to get the Xbox URL). It shouldn't take very long for them to be fully removed, but I'll look into why it's still appearing.