Is it necessary to remove can paint from a car before painting it?

You got to remove the clear coat at least you can paint patches as you need and blend the paint by fading it out instead repainting the whole car witch take experience to achieve proper finish. Patches and panels will be easier to do a diy job that will impress your friends. Color match is really hard to get on your own that is why blend the paint the clearcot will return the car to its original state do not worry if it looks dull around the patch. Sand after 16 to 24 hours using 1200 grit wet sand until no more orange peel buff using compound and enjoy