I read somewhere that use of a hair drier on a "warm" setting, a flat knife and some cardboard to protect the paint.
Basic process is to heat the badge/bonding, place the card next to it, and prise the badge off with the knife/screwdriver taking care to avoid contact with the paint. Try to keep the blade between the badge and the backing, not the backing and the car.
Then once its all off, you might be left with some backing/glue. Remove with a little tar remover.
Wash the car, and polish and wax the area the badge was present.
Im sure the others will tell me if this is wrong.