Originally Posted by Anthony@FontanaNissan

pop up the shifter console, drip the shifter shaft with a channel lock or pliers (I would use a rag around the teeth of the lock / pliers to not gouge the shifter), and hold it in place while twisting counter clockwise on the knob.

NOTE: you can actually damage the linkage to the trans by simply trying to unscrew and force the knob off without holding the shifter in place!