At the end, pour in coolant + water in 50:50 ratio in radiator, as well as reservoir bottle. Start the engine, let the cap remain open for sometime, and see and check that whether air comes out or not.
When temperature gauge is in the middle, or, Blue light for cold engine goes OFF, let it run for sometime, remove any / all air, turn OFF the engine and close the cap.
To me, this seems a reasonable way for radiator flush.
You can also watch some videos on YouTube on how to perform this.