DISCLAIMER: This method applies only to badges that are applied with adhesive. In addition, I take no responsibility for you messing up your paint job if this doesn't work for you. I've used this method de-badging 2 Audi's (b4 platform) and 1 BMW (e36 platform).
Tools needed:
1. Hair dryer
2. Dental floss
3. Clean soft towels
4. Your favorite type of adhesive remover (make sure it's clearcoat/paint safe)
5. Wax
Procedure:
1. Heat up the badge with moderate heat from the hair dryer. Don't over bake it Just get it warm enough to make the adhesive pliable.
2. Run the dental floss behind the badge and pull it in a sawing motion in one direction. You may need to stop and re-heat the badge if you get stuck in some places.
3. Once the badge is off. Apply your adhesive remover (or just rub it with your finger and some wax) and gently rub off the glue spots.
4. PATIENCE PATIENCE PATIENCE. Work slow and on little sections at a time. If you rush this you will scratch or mess up your paint.
5. Once all of the glue is off. Hit up the section with a good coat of wax.