As the other users have said, breaking the plastic with something kinda heavy and/or cutting it out works (@leloyon said its a bitch to use the scissors though, and it's 100% true). I'd break the plastic from behind with a heavy glass candle lol, then attempt to "weed out" the individual blades with scissors. But be careful! If you hit it hard enough you can break tiny pieces off the razors, and they can be difficult to see. It's bad news if you get a shard of metal in your cuts (or have someone step on a tiny piece unknowingly).