Ducati ST4S Owner's Manual page 178

Unscrew the 8 fastening screws (3, fig. 63 - fig. 64) that
hold the headlight fairing to the side body panels.
Remove the fairing sliding it off the headlamp.
Important
When refitting, it is necessary to loosen the screws
of both rear-view mirror mounts and then fit the headlight
fairing. Make sure turn indicator cables are not squeezed
and fit rear-view mirrors with the relevant gasket, secure
E
them with screws (1, fig. 61).
Set the headlight fairing so that its top edge is horizontal.
Tighten screws (3, fig. 63 - fig. 64) starting from the front
ones then tighten mirror mount screws previously
loosened.
68
3
3
3
fig. 63
3
3
fig. 64