Perforate the wallpaper with a utility knife, taking care not to damage the wall itself. Wallpaper-scoring tools are available and designed to perforate the paper and lift it up as you go along.
Perforate the wallpaper along the trim and in tight corners, using the utility knife.
Apply a wallpaper remover gel to the wall with a paint roller. Use a paintbrush to apply the gel in the corners where the roller could not reach. Leave the wall alone so the gel can soak into the wallpaper. Allow 30 minutes or the amount of time recommended by the remover gel manufacturer.
Pull away the old paper gently after the wallpaper loosens from the wall. Begin at a corner of the wall. Take your time to avoid removing any part of the wall's surface beneath the wallpaper.
Scrape off any remaining wallpaper and glue from the wall with a putty knife.
Clean and wipe down the wall with a wet sponge.