twist and pull... twist and pull... etc etc etc...

A small flat head screwdriver works too but you need to be careful for 2 reasons:
1) you don't want to cut up the hose and more importantly...
2) you don't want it to slip and slide across your finger(s), gashing it open as it goes.

Just depending, it might not be a bad idea just to go ahead and replace that hose while you're at it anyway. That PCV valve generally isn't that hard to get out or at least it shouldn't be.