First, get a wall paper scoring tool like this:
http://www.lowes.com/...L=1&productId=3036950
There are several makers of them and their inexpensive. At the same time you're buying the tool, look for a liquid wall paper remover... here in the U.S. the brand of choice is Zinsser.
Next, run the tool all over the area to be removed...he more the better... warm the removal liquid and place it in a gallon plastic pail. Get a couple of rolls of inexpensive paper towels. Lay something to protect the floor from drips, soak a goodly section of paper towel (maybe 3 to 5 feet long) and then, squeezing it out only slightly, begin at the top of the wall and just lay it against the area. It will stick if you'll smooth out the air bubbles. Make sure the wet towels come into contact with the whole wall area and leave it for about 10 to 15 minutes.
Come back to it and start a small section peeling at the top of the wall, where it meets the ceiling and it'll strip off in sheets. Keep a spray botte filled with the warm liquid to spray if an area starts to dry out.
Only caveat, you're gonna hope the people that applied it originally, "sized" the wall underneath the paper. If not, all bets are off, since the paste on the back of the wall paper has worked it's way into the untreated wall and life isn't pretty with all that scraping and cussing... (make sure the kids are ut of the room).