Answer:
You can't do that, but you can extract potassium chloride from the charred remains of the potassium chlorate reaction. If you melted potassium chlorate in a test tube and dropped sugar or anything containing carbon into it, the reaction will produce oxygen, water, carbon dioxide, and potassium chloride. The potassium chlorate would have vaporized from the reaction, so you can just scoop out the powdery stuff in the test tube and that's potassium chloride.