How do you remove putty from wooden windows?

Vanishing Varnish First of all, if the varnish is dry, you could try to scrape it off with a razor blade.

Another method you can try is to use paint thinner or stripper. Apply the thinner/stripper to the varnish you want to remove from the glass, and let it sit for 30-45 minutes. Then wipe off the excess and finish by scraping the remaining softened residue with a razor blade. Follow that by cleaning the window with BonAmi (available for purchase online; see the Related link below) on a clean cloth, using a circular motion. Rinse, then mix 1/2 cup white vinegar to 1 gallon warm water, and finish cleaning for a sparkling clean window.