Small stone scratch on windscreen, best way to remove?

If the scratch isn't too deep then try buffing it out with bro or chrome cleaner. Apply just a little at a time on a duster or cotton wool ball and rub over the scratch in circling motion until it forms a "powder " residue then polish off and repeat this until it disappears. Thoroughly wash your windscreen after. This will take some time but it should work. I hope this helps.