| Steve,
To drain the system completely, first remove the drain plug from the side of the water pump cover and then remove the drain plug from the bottom of the coolent outlet on the side of the horizontal cylinder. That will empty the system completely.
When refilling use a solution of de-ionised water (cheaply available from Halfords etc) and Shell Advance Coolant or Glycoshell at 35-40%. ie 6 parts water to 4 parts Shell Advance. That info is straight from Ducati.
Hope this helps.
P.S. System holds 3.5 litres in total. | 
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