Rub cooking oil all over it. Cover in a plastic bag. Let it sit for 24 hours. Take a Brillo pad and scrub it. The rust should come off. Wash with dish detergent and dry off. Then put on stovetop burner turn it on high to dry it out. It takes just a few minutes. Let cool and store in a dry space.
Melody is telling you correctly. The only thing I do differently is dry the pan and then turn it upside down in my oven to let it finish drying out before I store it.
Do you have to apply oil again before storing?
I do after the initial cleaning. I use paper towels to wipe off all the excess. After that, I just wash and dry and put in the oven. I don't reapply oil each time before storing.