Scratches on series 7

You can check with a local jewelry repair site and see what they recommend on dealing with the scratches (you cannot remove them) or you can do an out-of-warranty replacement of your watch (they don't do screen replacements). Click on the Get Support link on the top right if you want to start the service process.

If you have minor scratches on the screen, I'd recommend putting a good quality screen protector on the screen. It will most likely hide the scratches you have and prevent future scratches. Best Buy and Amazon are two great options for screen protectors for Apple Watch.