The part is threaded into the center of wheel mount. It just unscrews. It has been a couple months since I did mine but if I recall correctly I just kept moving it with lever, and remounting lever in next holes until it could be moved by hand.
If you have a pin spanner wrench to put in the two center holes it would be easier. I think I opened up a needle nose plier and put it in the holes and used it as a handle to spin it out.
You will need a wheel puller once you get all that out of the way. If you don't have one I used a piece of steel, and three bolts to do mine.
Just unscrew the center bolt until it pushes the wheel off. 5/16 in. 18 threads/in. IIRC?