Kelsey Hayes rotors

In the meantime, unless they are damaged, use them. If you take them off, one side can be cleaned of rust on a flat surface with fine sandpaper or cloth. The process of flattening and resurfacing this way is called lapping. The hat side will have to be done with a block.
The rubber & grit 'rust erasor' might work too. Don't be too aggressive with that or might remvoe metal and then the surface won't be flat. Probably OK doing by hand. I've used them for other things but not rotors.