you can take it to a shop to do it with a machine, buy a flush kit or do it yourself: Drain the radiator fluid, fill it up with water; this will dilute the remaining antifreeze in the engine block. Start the engine, allowing it to reach operating temperature. When the engine's cooling fan turns on, it is an indication that the thermostat has opened, allowing the freshly added water to circulate through the engine thus diluting the remaining coolant. After the engine cools down, drain the system. Refill it with coolant and distilled water. Remember to do the proper mixture.