Remove all switch plates and outlet covers from the walls, and move furniture out of the room. Spread drop cloths on the floor at the base of the walls where the wallpaper is being removed.
New wall papers have vinyl coating, and multi layer wallpapers are designed to prevent water from getting in and softening the glue which is what gives them the washable properties. Make some holes in the wallpaper surface to allow the water to penetrate. Scoring the surface lightly with a utility knife or the edge of a putty knife can work, but there’s the chance that you may cut too deeply, but if you have a drywall, you may actually puncture the paper surface on the underlying drywall. Your option would be to use a wallpaper-piercing tool available at a home store. The insides of the tool are made up of a series of spiked wheels that pierce the wallpaper as you roll it over the wall, making lots of little holes so moisture can get through the surface and down to the glue.
Once the wallpaper has been scored, wet the walls with a solution of warm water and vinegar using a spray bottle or bucket and sponge, and leave it for 30 minutes. Non-toxic wallpaper remover is also available. Simply mix it with water and spray over the wall.
After 30 minutes, pick a corner or a seam and gently peel back on the wallpaper. Use a wallpaper scraper held at a low angle to scrape the paper off in sections if it does not come off easily. Keep a spray bottle of wallpaper remover handy to spray stubborn areas as you work your way across the first section. Peel and scrap the wallpaper as you work.
Clean Up and Repairing the Walls
Use Tri sodium phosphate (TSP) mixed with warm water to wash the glue off the walls after the wallpaper has come off. Rinse the new cleaned walls with clear water to remove any traces of the TSP.
Repair any holes that the scraper made in the drywall. Fill small holes with drywall or spackling compound and smooth them out. Allow to dry overnight, then sand the repair, prime and paint.
If you’ve made some large holes on the drywall when scraping off the old wall paper, paint the exposed gypsum wall with white shellac, which will prevent moisture in the drywall compound that you use to patch the holes from soaking into the interior of the drywall and cause bulges. Then, patch the holes with drywall compound, let it dry, then sand and prime it.