[Antonella]

Rule 3 - EQUIPMENT
Sec.6: PROTECTIVE EQUIPMENT
f. Helmet
(...)
2) Deliberately wearing the helmet improperly or deliberately removing the helmet during a live
ball play, except on a home run hit over the fence, and seen by the umpire as a deliberate act shall
cause the violator to be declared out immediately. The ball remains live.
EXCEPTION 6-f-2: If a thrown or batted ball contacts the deliberately removed helmet, the ball becomes dead and
runners must return to the last base held at the time of such contact.
NOTE: Calling a runner out for removing a helmet deliberately does not cancel any force play situation.

This is ISF.
See what? You cannot find this ruling under Rule 8.
Nothing like 'Runner is out when...'

That do MEANS something to me.

Ciao