Purchased horses refuse to wait
Sadly, you cannot get horses to wait. But, you can go to Katla's farm, pick her wheat and sell it back to her. You will then be able to take the horses from her stable for free. These horses will NOT be owned by the player and will walk back to their home (Katla's farm) when you dismount.
Take one, (for free), kill that horse, (being the one that follows you), then no horse will follow you.