I recently had the same problem I used a tire iron wedged between the lug bolts and the ground and then used a breaker bar with an extension or piece of pipe and I finally got that sucker loose.
*I had to replace the hub because the gears or splines inside were wore out and the axle was spinning inside the wheel.
*I guess this is a common thing with these carts at times and this is a fairly cheap fix!
*Usually it was a battery too low charge thing but this time it was different the engine I could hear was running but the cart was not moving in forward or reverse.
*I looked at one of these sites on the internet and they gave me the answer or solution to my problem. In my ongoing education in golf cart maintenance.