I used to work for a sign company, applying vinals and such to cars. We often had to take off dealer badges. We had 3 different steps, depending on how drastic the badge was applied.
Your first step should be to take a blow dryer (industrial if you have it). Heat the badge up a bit, but still touchable, and try slowly peeling it. The heat softens the adhesive. If you want, you can also break the bonds down some with household rubbing alcohol.
If that doesn't work, there is a spray called graphix gone, it is orange oil based, and eats at the glue residue.
The final step is a remover from 3M. I can't remember the name, but it is expensive, and needs to be tested on a non visible area of the car first.
All these steps will require you to wash the area and rewax when done. but it should all work. Also, never use metal to pry, try to find some softer plastic pry tools if you feel the need to pry anything.
-Joe