I would pump for a few minutes to relieve the pressure, and then wait it out again for a while. Eventually, your body will understand that you are weaning and gradually stop. If you let it go, you may develop plugged ducts or mastitis which is painful and dangerous and you will need an antibiotic to clear it up. Take a hot shower and let it spray out, that works too. You probably shouldn't just stop "cold turkey" but let your body do it gradually.