Apply heat to the border. Set the blow dryer on high and blow dry the border, holding the blow dryer 10 to 12 inches from the surface of the wallpaper border. This will melt the adhesive on the border for easy removal.
Scrape the border. Use the plastic putty knife to scrape the border, lifting it from the wall. Begin at the seam of the border and work your way around the room, lifting off the border as you go. If the border tears during the process, apply additional heat before continue to scrape the border at the tear spot.
Soak remaining wallpaper border. Apply the water and detergent mix to any remaining sections of wallpaper. Use the rag to soak the border until it becomes slightly transparent.
Remove the remaining wallpaper border pieces. Use a sponge to scrub away remaining sections. Scrub in a circular motion to lift the corners and scrub away any remainder.
Clean the wall. Dip the rag in the dish soap water and gently wash the wall. This cleaning process will remove any small pieces of border on the wall, leaving you a nice clean surface.