The easiest way to flush a cooling system is to remove the radiator cap, open the radiator drain cock, let the coolant drain, move the dashboard temperature lever to hot and remove the pressure cap. Next, open the drain cock and disconnect the hose. Then refill with water and repeat.
Always start with a cool engine and check the specs to see how much coolant is in the system. To disconnect the hose after opening the drain cock, move the hose clamp back from the radiator neck, use a screwdriver to free it up and then twist it slightly to disconnect it.