Deep scratches aren't worth it.
Light scratches can be done, you buy a kit (sorry I don't have the link, try google). But it's a little like making your own optics for a teliscope. You sand with finner and finer grit until it's clear. IMHO, deep scratches can't been done yourself.
my advice, live with the scratches or dump the monitors.
Oh, ya, you might read online to use teeth whitening toothpaste, doesn't work!