I just used Mr. Clean on the chrome from a Polar Lights Klingon D-7. I tested it on a sprue first, let it soak a couple of days, and all the chrome was completely dissolved, with no harm done to the plastic. Then, I let the kit pieces soak, and after a few hours, the chrome was gone. It did leave a greenish film on there, but I've heard that was a carrier for the chrome, and it sanded off easily.
I mention Mr. Clean because it is easy to get in the states, and many people already have it. It didn't take much, either--I filled up a Model Master clean paint bottle with it. All the kit pieces fit in there, so it took less than a half an ounce or so.