Many localities or states prohibit disposal of CRT's in landfills, so doing so may be illegal first of all. I think I've read CRTs contain about 5 pounds of lead in their glass for protection from radiation, and hazzardous phosphors as well. However if it is legal to dispose of them in your area, you can simply bust off the back end of the tube letting air in and that will remove any charge at the same time, and now just be a heavy hunk of toxic glass with a sharp broken end.