It depends. Castor oil appears to pass thru the kidneys according to Dr Jennifer Daniels , so that can help. The main question is how do you know you have kidney parasites?
If you have kidney parasites there would be stones in the kidneys harboring them, otherwise, the body would flush them.
If you are referring to chronic bladder infections or UTI's, that again would be stones.
If there is a pathogenic process damaging the kidneys, that would require something else.