actually, women who use a breast pump (enough) can produce milk even when they haven't had a baby. but yes, get your hormones checked if you have milk and don't want it. It's called galactorrhea. Google it.
If you are saying that you have breast milk, and have not had sex, you might go to the doctor's and get your prolactin levels checked to see if they are out of whack. If you are saying you want to produce breast milk, see your doctor, but I don't think there is any way to make that happen without having a baby.