when i was replacing everything, my pcv valve wouldn't come out either, because the rubber grommet was so hard and dry. i wasn't concerned about how it came out, since i was going to replace valve cover gaskets anyway. i put a big pair of vise grips on its and just yanked it out. once pcv was out, i cut the grommet out, and bought a new grommet at the stealership for a few bucks. new pcv slides in/out of new grommet real nice.

 

I recently changed mine and had the same problem. The valve was so brittle that every time you pulled/twisted it ,it would break off in small pieces. Eventually I was left with the rubber grommet as bits of the valve had fallen in the cover.The grommet needed replacing as that was also very brittle.As it was so brittle I had to cut it out in small pieces and push bits into the cover. The valve cover has an inner skin so any bits of valve or grommet you push through will not dissapear into the top of the engine.You must then remove the cover and shake theloose bits of valve and grommet out .
I had never done this before so it was more trial and error rather than the correct way of doing the job. I did replace the gasket but that was more for peace of mind....