Delete backdrops in Photo Booth?

This is a Photo Booth question, but I couldn't find a forum that would fit. Maybe I'll post it under Leopard as well. The new photobooth effects are really cool, but I tested the "backdrop" function with some random picture, and want to delete it. I can't figure out how to do this! I'm sure I could just put a different picture in its place, but is there a way to remove the backdrops? I can't click, ctrl-click, or right-click without it just selecting the effect. Thank you.