You can use vinegar to remove wallpaper. First, remove the top layer wallpaper. Put one cup of white vinegar in 1 gallon of hot water and use a garden sprayer or sponge to soak the paper.
Leave to soak in for a minute or two. Then pull the backing away. Scrape the excess glue off of the wall. Wipe the remaining glue off with vinegar and rinse it well with water.
You do not have to use harsh chemicals and this way is much cheaper.