If you find light patches of rust on your cast iron, you can use some elbow grease and steel wool to scrape it off. For stubborn rust, you can opt for an easy home remedy. Make a solution of water & vinegar and soak the rusted part in it for an hour. You can leave it a little longer based on the level of rust. But do not go overboard with the time. After soaking, scrub off all the rust from the pan. Furthermore, thoroughly clean your cast iron with hot water, dry it well, and season it. Lastly, to protect your sink from all the rust, it is better to use a separate arrangement. You can do it in a disposable aluminum pan or a plastic bucket of the desired size.