When I buy a whole chicken I remove the kidneys and anything else left by the inferior butchering method used. I rinse it in running cold water then fill the sink with cold water & salt and clean it out well. It is now ready to roast and maybe stuff.
I frequently buy 10 pound bags of leg quarters as they're so cheap ($6 - $7 U.S. per bag) . If there is any backbone remaining on a quarter that gets removed along with the kidneys. I then wrap and freeze them individually. A leg quarter usually gets slow cooked in a pan for 2 - 3 hours with herbs & seasonings and maybe onion and / or garlic. After it cools I de-bone the quarter and the meat then goes into a recipe or on the dinner plate.