Hi Mike,
On the back of the headstock where the draw bar enters, you would remove the oil dust cover then the nut. If the nut is a split nut I use a simple wrench I made that has a lip that enters the slot in the nut. If the nut isn’t a split type nut then I put a rag around the nut for protection and grab it with the inside circular part of a plier. It should back of fairly easily. Loosen the set screw on the spindle and put a piece of wood on the back of the spindle and lightly tap on the wood to move the spindle out the front of the headstock. I also use some light penetrating oil on the spindle to help loosen it up before tapping it out. I don’t know if that is the recommended procedure but it has always worked for me.
Good luck, Dean