I think the best practice is to use strong thread / dental floss. Just carefully cut behind the letters, perhaps wetting the area will provide sort of lubrication to reduce stress on the paint, some guys show that they had heated the area, but that needs to be very carefully dealt with not burn yourself of paint.. Letters are attached VIA industrial adhesive which is kind of foam based, like thin automotive 3M double sided adhesive. If you search Youtube, there should be plenty of examples.
look here or search ""removing car emblem" https://www.youtube.com/watch?v=febXx3r0RWs