Chosen Solution
The car does not have proper traction and I think there is a problem in the gearbox between electrical engine and rear wheels. I disassembled the car but I could not take out the engine and gear box because of the rear axle. I tried to pull off the rear wheels to remove the axle but it did not work. Any ideas how to do that?
The answer is: brute force. The only way to remove the axle is by taking the wheels off first. They are pretty tight, but I managed to pry them off using a fork. Insert the fork all the way down behind the wheels, with the axle in between the tines of the fork. This will prevent the wheel from getting too damaged. Then use the leverage of the fork to pry the wheels off.
