A pet tamer is an NPC who will take player's animal companion off their hands. If the pet is level 20 when given away, player will receive 100. Pet tamer gives no gold if the pet is below level 20 or was summoned by the Zaishen Trainer Captain.
Once an animal is charmed, this is the only way to get rid of a pet. Before acquiring a new pet, the old one must be given to a pet tamer. The pet must be present (i.e., Charm Animal equipped) to be released.