I have cut many of the older ones with no problems. Open the valve and turn it upside down and leave someplace where the sun can work on it. Propane is heavier than air and the heat from the sun expands whatever gas is in it and drives it out. When the sun goes down, the bottle cools and draws fresh air into it. The next sunny day repeats the process and after several days, you have respirated all the flammable gas from it. When I am ready to cut, I heat the bottle with a rosebud and occasionally I run the flame by the open valve. If there is any flammable gas in it, it, it will ignite and burn briefly. If it does not light, there is no flammable gas in it. If it is a newer bottle you want to cut, a fitting needs to be screwed into the valve as the new valves need a proper kind of fitting screwed in to activate the safety valve while it sits in the sun and respirates.