Not sure how he did it but one trick is dental floss behind the letters worked back and forth. It will cut though the adhesive pretty easily. Then take some adhesives remover to remove the residual left over.
I used fishing line. I tied 2 1/4 nuts to a piece of monofilament. The nuts will keep from string cutting fingers. Slid behind the letters and move back and forth cuts right through. Then a blow drier lightly heat up remaining adhesive and roll out with your finger be careful no finger nails. Remaining glue use mineral spirits rub lightly and when complete wash and apply wax.
The front side marker was driving me nuts being that Brite ass orange. Once I got started it only seemed fitting to go all out. It's not a daily drive car. It's the Friday Saturday night cruise with the family car. Occasional car show car. What color is your car. I have a buddy doing his scat pack B5 in blue tint. Should look good.
There not hydro dip. Hydro dip of Houston did the work for me.
There painted. They use clear and add black paint to the mix. Side markers are 2 coats as is the back except the turn and backup light area they are single coat. Then there wet sanded and buffed out. This is a no going back process. You can lighten them some by wet sanding and rebuff. They applied the first coat and checked it for darkness. Then add more coats as needed.