I bought a can of adhesive remover. I soaked both 6.7 badges, let it sit for a little while. Then focused on one badge at a time. I used a small piece of copper wire (size of dental floss), and slide the wire behind badge where the adhesive pad was. I slide the wire up and down making sure the wire stayed next to the plastic badge, not against the truck. It cuts the adhesive pad, and helps get it off. I was a little skeptical about using the wires, but I didnt scratch my truck, but was super careful not too.
I took my time, used plenty of adhesive remover, and eventually it came off. After I got it off, I washed the truck to get the adhesive remover off. I waxed it also.
I havent taken the "350" badge off yet, but would like to know how also