The radiator has a drain fitting. You don't have to remove the hose. You don't need to remove the expansion tank either to refill. Remove the cap from the expansion tank. Open the radiator drain fitting and drain out all the coolant. Close the drain fitting. Then refill with a 50/50 mix of coolant and water until the level is at the bottom of the expansion tank. Start the engine with the cap off and run it until you see the coolant start to flow through the thermostat. You can also move the heater control over to hot so it flows through the heater core.