If the decals are new and not badly weather-worn, a hairdryer and you can often just peel them off. They were dry and cracked on my
Scamp, and the only thing that worked for me was a plastic razor (in the
paint section of hardware stores) with plenty of extra blades, time, and elbow grease.
Some have had good results with a 3M “magic eraser” wheel on a power drill. I tried it, but it smeared ink from the decals into the pores of the gelcoat- very hard to remove.
On an older trailer, removing decals will leave a ghost image of unweathered gelcoat. It’s not ugly, just noticeable from certain angles, and it’s still there four years after I removed mine.