I removed and replaced my 5er decals on the front and rear last year. Started with a heat gun and plastic scraper. That worked fairly well with decals that were still semi pliable. I could get an edge lifted and with just the right amount of heat could peel off fairly large pieces. But decals that were really cracked and brittle, not so well. They would come off in very small pieces. A lot of adhesive left in both cases.
Bought a 3M eraser wheel. Have a strong 3/8" corded drill. That was much easier. The decals would come off under the wheel in flakes taking a lot of the adhesive with them. I don't think a battery powered drill would work well.
In both cases, I removed the left over adhesive using 3M adhesive removed. Bought a quart can at O'Reillys auto. Worked very well. I took an old towel, held it below a section of adhesive, squirted a stream of adhesive above and across that section of adhesive, let it sheet down over the adhesive, and soak into the towel. Then using the thoroughly soaked towel just wipe the adhesive away. With enough remover in the towel. the adhesive will essentially melt and soak into the towel.