Use alcohol and elbow grease If done correctly, this method is a reliable way to remove any stickers from the glass with minimal risk of damage. Spray window cleaner or rubbing alcohol onto the sticker and allow it to soak in for 10-30 minutes. Then scrape with a razor blade to remove the leftover sticker and residue.
Alcohol, nail polish remover, spray lubricant, vinegar, and lighter fluid can all remove adhesive from glass if water alone doesn't work. Apply with a rag or cloth, then rub the glue away.