Before you start be aware that wallpaper removal can be labor intensive and could cause severe damage to the walls. Most removal damage is due to the lack of a wallpaper primer before the walls were wallpapered, resulting in the glue being absorbed into the wallboard. The top layers of wallboard (paper) will try to come off with the wallpaper backing. If this occurs in large areas, call a professional.
There are many different types of wallpaper on the market today. Some are dry stripable, solid vinyl and fabric backed papers can usually be removed by simply pulling them from the wall without wetting.
Most residential wallpapers are of the " vinyl coated "type. Vinyl coated papers are by far the most common in residential homes. The vinyl face of these papers is usually "dry stripable" meaning that the face will separate and leave only the paper backing on the wall. Start by removing as much as the vinyl face as possible. Find a loose corner, you may need a putty knife or scraper to get started.
After all the vinyl face is removed the paper backing should also be removed. The paper backing will require a wet removal. Fill a five gallon bucket to about half full with warm water, add about a cap full of fabric softener. Turn off the electrical power to the room. Apply this solution to the wall with a paint roller or garden sprayer, a sponge can be used in corners. Wet a four or five foot section of the wall and make sure the wall section remains saturated with the solution for about ten minutes. Remove the wet backing with a four or six inch putty knife or scraper.
After all the backing is removed finish cleaning the walls with a hand sponge and fresh solution of fabric softener and warm water. Allow the walls to dry and apply a wallpaper primer if you plan to re- wallpaper the walls. If you plan to paint apply an acrylic primer/sealer to the walls before painting.
This is messy work be sure to place rolled towels or bed sheets at the base of the walls before wetting them in order to catch solution runoff.
Do Not spray or saturate electrical outlets or switches with the solution, turn off the electrical supply to the room before wetting the walls.