Use a heat gun or blow dryer and warm them up. Then peel them off. They should come off ready easy. If there's any sticky stuff left use some goo gone on it.
If goo gone doesn't work on the goo try laquer thinner. There is also a 2 part product with a name that escapes me at the moment. I think it is 2 types of spray that you apply one after the other. I used this on a toyota I have to remove the decals from. Worked great with little mess or effort.
what worked awesome for me was to set it out in the sun for about an hour on a hot day and then start peeling. almost every decal came off in one piece.
Hair dryer is the way to go it is very easy. I have taken decal off on all my sleds with the hair dryer. Just heat the hold area and then as you peel keep heating in front of you as you go.
Lol yeah please use enought heat, I didn't take enough time to heat it completly and it ripped off the paint from the plastic. Turned into a new paint job, but in the end I'm glad it happened.