Use a propane torch cuz it doesnt get too hot... Heat up your prop and hit it with a mallet to get it sliding off the splines... If you can't get it off it sounds like someone didn't greas up the splines enough before they put the prop on... You want to be careful heating up the prop because everything is metal so it'll transfer heat. You don't wanna ruin the seals in your drive by heating it up too much. Don't hit the prop too hard...
If that doesn't work, I hate to say it but a chop saw is the next option...