A big concern has been raised on this site about this material containing asbestos. If you have an older home, the first thing I'd do is have a sample tested to see if it contains asbestos, if it does, the best thing you can do is leave it alone.
I believe that the best way to remove this texture is to soak it with water sprayed on with a compression sprayer. Soak an area only large enough for you to scrape off before the water thoroughly saturates the drywall. Wash the remaining residue off with a clamshell sponge and clear water. Repair any damage with joint compound (seal any torn surface paper with something like Guardz or Drawtite).
This is a messy project so you'll want to take the time to cover the room well. Keep in mind that plastic on the floor is a hazzard when your spraying water. Take as much out of the room as possible.