Are you removing decals or stickers? I have removed lots of stickers, even stickers over top or other stickers. As far as decals are concerned, I have not removed just those.

To remove a sticker, warm it up with a hair dryer, work a corner loose with a fingernail and then pull the sticker off. Do not pull away from the painted surface! Rather, pull the warmed up sticker parallel to the painted surface.

I have had great results with this procedure. Hope it is a help.