Check with your local landfill or waste management service as some will have programs where they accept hazards waste and they'd likely accept the old brake fluid.
Also check with auto parts stores such as Auto Zone as they accept used oil and would likely accept old used brake fluid for disposable as well.
If you have no programs that accept the brake fluid or other hazardous waste you can pour the brake fluid into a container of cat litter and it will evaporate and be gone and then you can just pour the cat litter out on the ground.