Cover the floor and furniture with plastic dropcloths to prevent them from getting wet. Cover electrical outlets with masking tape.
Start in a corner and peel off as much of the vinyl wallpaper as possible. Once one sheet rips off, pry back another piece and continue peeling until you can no longer remove any of the wallpaper.
Press a wallpaper scoring tool all across the wall. Even if only the backing is left from the vinyl wallpaper, this needs to be scored. Perforate the wallpaper with the scoring tool at least every 2 inches over the entire surface.
Mix 2/3 cup of hot water and 1/3 cup of fabric softener into an empty spray bottle. Spray the mixture generously onto the wall and allow it to soak for 15 minutes.
Scrape the remaining wallpaper, backing and adhesive from the wall with the putty knife. Apply more fabric softener mixture and scrape again until all of the wallpaper, backing and adhesive are off the wall.
Clean the wall with a sponge and warm, soapy water to remove any residue.