Procedures will vary depending on model and equipment fitted.
NEVER open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Avoid physical contact with the coolant. Wear protective clothing and eye protection. Always drain coolant into a sealable container. Clean up spills as soon as possible. Coolant can be reused if it's reasonably clean and free of debris. If you suspect it is contaminated, or is more than a couple years old, it should be replaced.