Before you resort to any heavy methods, start with what you can do easily. Warm the pans up with some oil in them and wipe them out. Often on pans this will get nearly all the rust off. What more there is I'd take off when warm, with edible mineral oil, and 0000 steel wool and elbow grease.
Sure, you can sandblast, or do electrolytic derusting, or otherwise strip it to completely bare chemically clean iron. Which will nearly instantly rust again. Don't use anything with phosphoric acid in it (naval jelly) because of possible poisoning.
I bought a Griswold lamb cake mold off ebay once that was rusty when I got it, just like your pans. A little heat, a little oil, and the rust wiped right off. That lamb cake mold looks like new today.