I'm going to drop a dog off on the side of the road
Why are you going to abandon that dog?
The dog always poop inside the house and I can't train him.
If you do not want to take care of your pet anymore, there are more humane and ethical ways to get rid of it. You can gift it to your family and friends, or drop them off to a shelter. It's cruel to just drop them off the road.
Who cares? It's fine if they starve or get hit by a car.
When you adopted that dog it was your responsibility to take care of it. That includes giving it a proper chance at a life, even if it means with someone else. Putting it in a situation where it might die isn't just giving up on it, its intentionally being negligent of its life and it says a lot about you as a person.