I am not sure if there is an effective home scratch remover for glass. There are glass polishing systems the pros use - it involves power polishing with decreasing size honing compound. If you have a huge scratch, you might try a glass or auto windshield place & see if they have any experience removing scratches from aquariums.
The simplest solution, if you just have one pane scratched, is to turn the tank around so the scratch is at the back & no one will see it!
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.