I attempted to use my tub drain removal wrench to remove a bath tub drain. Unfortunately the spokes of the drain broke and the drain flange cracked. Not being terribly skilled at plumbing I am now unsure of how to remove this tub drain. How do you remove a tub drain with no spokes and therefore no removal wrench?
You could try putting an expanding plug into the drain which should give you something to grab hold of with a pair of vice grips. I would replace the wing nut with a regular nut so that you have better access to the stud.
Another approach is use a large pipe extractor, which looks similar to a large left handed screw, and bite into the drain trim, and back it out. You will get more torque with this approach, but the pipe extractors are pricey, especially in that size. One brand product is called EZ-out.
You can also use expanding pliers. I once saw a pair of arc joint pliers which were ground with DIY jaws on the back side, to accomplish the same.