How to remove rust from cast iron griddle?

First, remove the rust by scrubbing with steel wool. Then clean the skillet well in hot, soapy water, rinse, and dry with paper towels. Then re-season it by coating lighrly and throughly with vegetable oil and heat the griddle in a 350 degree oven for about an hour. It should be as good as new.

Also, besides the instructions someone else has already given you regarding how to reseason your cast iron, when you clean it from now on, if you've gotten it seasoned properly, you should be able to wipe out whatever you have cooked in it with paper towels. Don't wet it at all. But if you do get it wet, be sure to apply a light coating of oil to the surface again once you have it cleaned. This will keep your skillet ready for its next usage. I have a 10" skillet that I didn't wash in the traditional sense for at least three years until the lady that was cleaning for me decided one day that she wanted to see if she could get the skillet looking new and shiny again. Apparently she had never cooked with cast iron previously. Needless to say, I asked her not to touch any of my cast iron again, that I would take care of the cleaning of all of them myself.

Clean out the rust with steel wool or an SOS pad. Follow the instructions in the link below for proper care . I have many cast iron pots and pans I inherited from my grandmother and love cooking in them .

http://www.seriouseats.com/2014/11/the-truth-about-cast-iron.html

The easy way to clean an rusted or really. Baked on crud on the outside is to put it in the oven. Run the clean cycle. It will be good as new but must be

reseasoned.