Ernest, I'd see if a Radi-plane wouldn't give me enough relief. This is a very handy small hand tool, and works much like the old-time hand planes, but has a chamfer groove with an adjustable radiused blade in it. This would go very quickly, and be much safer than attempting to alter the quarter round with a power tool. One other option would be a power plane; I've found my 3-1/4" Makita power planer to be invaluable for things like this, and it has a chamfer groove down the center which makes for safe work on items of this nature. But I'd go for the Radi-plane if it's likely to be a one use tool. If I needed more than what the Radi-plane could provide, I'd use a chisel or utility knife to shave away some excess caulking.
As you've been following instructions, I know that you'll also remember to not nail through the Pergo, but into the wall.