We could try breeding the animals and flooding the market. I've heard that suggested for ivory.
Irrespective of the challenges their sheer size presents, they’re also relatively smart, and happen to live in conflicted territories. Convincing elephants that they should feel safe, and command enough familiar territory to breed openly is an additional complexity.
Is there enough room for 100,000 or a million more elephants? I’d like to think so, but what do I know?