It’s great you’re thinking about the planet!
You can recycle brake rotors; however, you can’t simply throw them into your household recycle bin. Contact your local scrap metal collection agency or junkyard to ask if they can scrap and recycle the metal of your brake rotors and if so, schedule a time to drop them off. That said, if your brake rotors aren’t metal, they may not be recyclable.
Call around until you find a scrap yard or junkyard that will repurpose the metal of your brake rotor—which can be a little more work, but it will be worth it to know your waste is not being dumped irresponsibly!