The best and easiest is with heat applied to the badge (Not a blow torch) but a heat gun similar to a hair drier. When warmed to the right temp use a piece of plastic fishing line pull it under the badge and this will remove the bonding. The adhesive residue can then be removed with a remover such as goof off or sometimes just by using auto detailer or wax.
Sad but true lol I just removed someones badges off of there focus this last weekend for them and all I used was fishing line.Exactly.
In Texas, we just leave the car in the sun for a few hours. It is as hot as a Heat gun!