From what I've heard, there are certain products in the store for that. Typical scratch removers will do. The actual LCD screen, here's a link for removing scratches haha
Most TMGC screens can be easily replaced, perhaps a local mall offers screen replacement nearby? Sorry I can't offer much,it really depends on the scratches too!
If you don't have access to Displex or other scratch removers, you might want to consider using the display piece from another Connection. Just be careful with the sound wires and use a small screwdriver head.
Yeah, as everyone before me said, use displex (not the touchscreen one). Just be careful about putting it on your tama, it can strip the paint off of it.