Paint is used on glass in many ways. It can be used to decorate the front of a store, advertise on car windows, or even as art on glass pieces. If you are painting on glass and made a mistake, or just want to change something that is outdated, you will first need to remove the old paint. How you remove the paint depends on how it was applied and adhered to the glass. For example paint that was sealed or baked on will be more difficult to remove.
Scrape paint off of smooth, flat glass with a razor blade. This will create paint chips and a bit of a mess. Keep a vacuum cleaner or broom nearby and clean up as you go.
Wash the glass with water. This works with some paints that have not been baked on. Use rags, but expect the paint to smear. It will take several washings to get it all off. Once off, clean the glass with glass cleaner to remove any residue.
Apply a solvent to the glass such as a paint thinner. This will strip off the paint easily as well as any sealants that are over it, but it does create fumes. Make sure you are in a well-ventilated area.