Your Leaf is too new. We've got an OG Leaf (2011) that had the old GPRS radio. When AT&T dropped that, Nissan generously offered a more modern cell radio for something like $300. Or they would take out the radio for free. Given the utter uselessness of Nissan's "remote" platform[0], guess which option we went for?

But it's right behind the glove box, and unless the design has changed (it has been eleven years), a couple of screws should get you in the neighborhood of the antenna.

[0] Seriously, what a slow-ass piece of shit. It was literally faster to walk out to the garage and turn the heat on than it was to do it through the app. And that assumes that Nissan's server could see its way clear to turn the heat on at all, which it frequently didn't.

If you can find the radio antenna you may be able to wrap it in enough foil and lead to stop transmission.

It's typically in the shark fin above the rear windshield, which is not easy or convenient to RF isolate.