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Yes 99% of all brands require this or the heat will warp the racks there is an exception as many GE models offer porcelain coated racks that are self clean approved so those you can leave in.
As far as cleaning the chrome ones baking soda and vinegar in a bathtub works very well and a scrub brush. Some people try putting ammonia in a garbage back with the racks but I don’t like the fumes it causes. I actually pressure washed my once I put a towel down on a piece of wood, soaked them in degreaser for a few hours and power washed them they came out looking like new!
