Go to any radiator armed a radiator key and a container to catch water also a cloth will help. Have somebody to watch the boiler pressure and vent off water from the radiator vent screw which you will find on the top corner of the rad.Take care if hot,being a Ferroli set pressure about 1.8bar hot or 1.5bar cold don't let the pressure go too low at cold other wise you may get F23 fault code which will lock out the boiler and need reset button pressing once pressure is over1.5bar, best to keep it 1.6bar when offline and cold.
Guytawe
June 2010