Ducati Monster 796 Workshop Manual page 364

Fork - steering head: front fork
Push downwards to overcome the force of the spring and remove the spacer (C).
Remove the service tool part no. 88713.0957 and slide out the preload tube (12).
Remove the spring (9) and pump the outer tube (18) and the damper (8) to expel the oil from the fork leg.
Warning
This movement generates pressure so that the oil will be rapidly expelled from the fork leg.
Aim the jet of oil into a previously prepared container and avoid contact with fork oil.
Clamp the inner tube (6) in a vice with soft-faced jaws.
Unscrew the screw (3).