Turn your radiator key anti-clockwise to open the bleed nipple, and enable the water to be drained into the bowl.
Once the radiator has been drained, turn your radiator in an anti-clockwise direction to close the bleed nipple again, before undoing the nut on the other side of the radiator.
Ease the radiator away from the wall and get rid of any remaining fluid. Remember, radiators can be much heavier than you might imagine, so you could require help when lifting.
Once all the excess water has been removed, use tissues to bung the outlets. From there, you can fully remove the radiator from the wall.
After the decorating is done, you can position your radiator back onto the brackets, tighten up the valves and open them both in an anti-clockwise direction. The radiator is then ready to fill.