3)
For vehicle with ABS
Pull out primary piston assembly straight so as not to cause any damage to inside o cylinder wall.
Pull out secondary piston assembly straight so as not to cause any damage to inside of cylinder wall and by tapping flange with a piece of wood or something soft.
For vehicle without ABS
Remove piston stopper bolt (1). Then remove secondary piston by blowing compressed air (2) into hole from which piston stopper bolt was removed.
Be cautions during removal as secondary piston jumps out.