The front brake discs consist of an inner carrier, which is mounted to the wheel, and an outer rotor. Both parts must be changed together as a pair.
Remove the front wheel (sect. 7 - 1, Removal of the front wheel).
Undo the retaining screws (5) of the disc to the wheel, remove the disc (7) and, on its left side, slide out the phonic wheel (6).

Removal of the front brake system
Overhauling the front brake componentsRefitting the cylinder head assemblies
Warning
To prevent oil leaks past the contact area between cylinders and
crankcase, each time the head is removed, cylinder and
piston must be removed as well to clean the mating faces of crankcase and
cylinder and restore the spoiled gaskets and
o-rings and apply again liquid sealant (sect. ...
Removal of the control unit
Loosen the screws (1) and remove the relay supporting bracket (2), disconnect
the connectors (3) and remove the control
unit (4) from the vehicle.
...
Refitting the clutch master cylinder assembly
Insert the clutch master cylinder assembly (3) and the clamp (6) on the left
handlebar, so that the top mating faces
match the mark (z) on the handlebar as shown.
Couple terminal (6) to the clutch master cylinder control and fix them with
the screws (v).
Tighten the retaining screws ...