Whats the best way to get this fitting off

I had to take an open hack saw blade and carefully cut a slit in the pipe. When it gets really close to getting all the way through, you can squish it with a pair of pliers and it will come out easily. Oh yeah, penetrating oil doesn't hurt.

You can speed up the process by using a cut off wheel or saws all for the portion of fitting that sticks out of the manifold.