I found these two links, both covering proposed methods of reducing poaching by modifying the tusks of the elephants being hunted. Both were accompanied with arguments for and against the proposed plans.
The first is thus: if poachers want tusks, why not remove the tusks of the elephants and rhinos so there is no reason why the poachers will hunt them? Expert Cynthia Moss shoots down the idea instantly, despite understanding the basis of taking away the source of the killing of these creatures. The number of wild elephants roaming Africa might be on the drastic decrease, but there are still too many out there for a proposed method such as this to be undertaken upon each and every one of them. Additionally, the cost of the procedure is too expensive, even if all of the elephants were in one area and able to be easily stunned in order for the operation to occur.
But most importantly, even if it were logistically possible, tusks are not easy to remove. An elephant tusk is a modified tooth, complete with nerves running all the way down them, which if cut incorrectly bring huge levels of pain to the wounded creature (as described here). A rhino’s horn is similar, and both have the habit of not fully healing after removal; an elephant’s tusk will regrow, while there is a case of a rhino having survived having their horn removed, only for the hole in their face never to fully heal.
Besides, elephants evolved tusks for a reason, and to remove them cripples their day to day activities. Everything from foraging to fighting would suddenly become a lot more difficult.
The second method face similar problems; one blog has suggested staining the tusks of the elephants with a harmless dye, in order to make the ivory worthless in the eyes of the illegal trade, even going as far as to propose a program for how such a thing would be carried out. Unfortunately, the number of elephants still roaming the wild of Africa makes this a logistically hard option to consider, despite the merited points that it raises.