Mix a solution of 1 part fabric softener and 2 parts hot water in a spray bottle.
Spray the solution along one of the seams of the wallpaper, at the top of the wall, covering a few feet. Saturate the area completely. Let it sit for 20 to 30 minutes, respraying the wallpaper as it dries.
Scrape under the wallpaper with your plastic putty knife at the seam. If the paper doesn't come up easily from being saturated with the fabric-softener solution, spray it again and wait a little longer.
Peel off as much of the paper as you can. Spray the next section, starting at the edge of the section you removed and saturating a few square feet. Repeat the process over the whole wall, letting one section soak while you're scraping off another. Take care not to damage the wall while you're scraping.
Mix a solution of 1/2 cup TSP in 1 gallon warm water. Scrub the wall down with the solution, using a nylon scrub brush, to remove any residual paper and glue. Let the wall dry for 24 hours before painting or repapering.