Well with they tighten on the axle you normal can not remove them. You pull the transaxle flip upside down, remove the case cover, the axle keepers, and then slide the axle and hub out. In order to replace the axle seal. This because the axle nut is torque to nearly 300 ft/lbs which cold welds the hub to the tapered shaft.
Even Tuff Torq does not sell just hub, they the hub and axle already assembled for that TZT1310 transaxle