I believe sandblast etch cannot be remove from the screen. The main reason sandblast etch was to deter theft in the first place, making sure registration is permannetly etched on the windscreen.
Thief used to replace car plates once a car is stolen, so etching on the windscreen would deter theft as replacement of the windscreen cost money.
Anyway, if you wanna experiment, try getting some rubbing compound and rub over the numbers on the screen. Removing the etched numbers is the easy part. Having the affected area polished, clear and good on the windscreen is the tricky part. G/luck!