Peel off as much of the sticker as possible
Rub the residue with your fingers to lift loose glue
Apply a small amount of rubbing alcohol to a cloth and wipe the glue
Use white vinegar on a cloth to soften the adhesive
Apply cooking oil, baby oil, or olive oil and let it sit briefly
Scrape gently with a plastic card or plastic scraper
Wash the area with warm soapy water
Repeat the process if any residue remains
Test any cleaner on a small hidden area first