Removing glue or any adhesive can be a challenge, but removing glue from glass requires a little bit more skill. Scraping and using any amount of pressure can cause the glass to crack or break so a little know-how is necessary. There are several simple methods for removing adhesive from glass that can make this quite easy. With a little time and the proper materials it takes almost no time at all.
Spray the glued area with WD-40 and allow it to soak for at least five minutes. Using a razor blade, gently scrape away the glue in small, even strokes making sure that the razor stays lubricated with WD-40 so as not to scratch the glass.
Soak the glass item in warm soapy water for 5-10 minutes. If the item is a window or something that can't be submerged, pour warm soapy water into a spray bottle and spray the area. If the area begins to dry up, continue to spray the solution onto it, keeping it soaked for at least 10 minutes. Use a clean cloth to scrub away the glue.
Heat the glue with a hair dryer to soften it and scrape it away with a scraper or razor blade. Keep the hair dryer moving so as not to hold it one place for too long, and until the glue is soft and pliable.
Cover the glue in peanut butter and use a hair dryer to melt it before scrubbing it away with a clean cloth. Use warm soapy water to clean the glass once the glue is removed.
Use a dab cloth soaked in isopropyl alcohol to saturate the glue. Allow the glue to soak in the alcohol for at least five minutes before scraping it away with a scraper.