Depending how bad the scratches are, it's probably not worth it, I've got a couple of scratched monitors, this one I think could be polished, using glass polishng gear, but that's not too easy, you need a very fine abrasive and a lot of time, plus in trying to polish, you inevitably take off the anti-glare round the scratch, someone else already did that for me

Don't use any coarse abrasive, it'll only make matters worse (Experieence talking here)
A possibility, though something I've been unable to find suitable stuff for, is to paint over the scratch with something that will fill it without leaving visible marks, and that will have a smooth surface, some kind of clear resin would probably be the answer...
But ultimately, you're going to make things worse not better, live with the scratches as they are, and be happy tom own a really nice monitor that isn't made by Dell