Is there anyway to sell cars on horizon 2 for the Xbox one at all
No, you can only “Remove” cars from your garage, which literally permanently removes them from your garage without any credit payment to you. By doing that, you basically just give up a car in exchange for nothing.
Nope. Don’t buy the cars you don’t want and, should you opt to remove them from your garage, you will lose all the credits you’ve invested into that vehicle.