Cleaning cast iron is easy. In our opinion, hot water, a rag or sturdy paper towel, and a little elbow grease are all your cast iron needs. Stay away from scouring pads, steel wool and abrasive cleaners like Barkeeper's Friend as they are likely to scrub right through the seasoning, unless you plan on re-seasoning after cleaning of course.
There’s a lot of debate about whether or not to use soap on cast iron. If you run into some tough grime, or you just feel more comfortable with a little soap, go for it. You’re not going to hurt anything. Just don’t soak your skillet in soapy water. We’ll repeat that one: never soak your skillet in the sink. Water should be used briefly and then the skillet should be dried completely. Some people like to warm up their skillet on the stove after washing and drying to be sure it’s completely dry, and this isn’t a bad idea.
Never put your skillet in the dishwasher. It would probably survive but we don’t recommend it.