Fill an empty spray bottle with equal parts Downy fabric softener and hot water. Shake the bottle to combine the ingredients.
Spray the fabric softener solution onto the wallpaper glue residue. Let the solution sit on the glue spots for 15 to 20 minutes.
Scrape the glue from the wall using a putty knife. Avoid applying too much pressure when scraping or you will damage the drywall. If the glue residue is tough, apply more fabric softener and continue scraping.
Fill a clean bucket with warm water. Use a sponge dipped in water to wash down the walls. Rinse and wring out the sponge often while cleaning the walls. Washing the walls with a sponge and water will remove any fabric softener residue.