What if the wheel is rusted to the axle how to remove it?

Spray the center with WD40 or some other type of penetrating oil and hit on the back side with a small sledge hammer. You can put a block of wood against the wheel so that you don't dent the rim. If they are aluminum rims, don't hit too hard or they will crack. Another way is to have the car on the ground and back the lug nuts out a couple of turns and rock the car side to side. This will sometimes loosen the rim. After you get it off, run a file around the center whole just a bit to prevent it happening the next time.