Ducati MULTISTRADA 1200S ABS 2015 Workshop Manual page 714

Replacing the rear sprocket
Slacken the chain (Adjusting the chain tension).
Remove the exhaust silencers (Removing the exhaust system).
Remove the rear wheel (Removing the rear wheel).
Restrain wheel shaft against rotation.
Remove the circlip (1).
Using a suitable socket wrench, loosen nut (2).
Fully unscrew the nut (2) and remove the washer (3) and the flange (4) with the sprocket (5).
Collect spacer (6).