Lift the innermost black lens barrel section away from the section with the gear teeth, which remains still engaged with the outermost section.

Rotate the geared section clockwise within the outermost section as far as it will go. This causes the flash head actuator to move forwards, then allowing the geared section to be partially withdrawn.

The geared section can now be completely withdrawn by squeezing the geared section and stretching the outermost section so as to allow two pips in the flash head actuator to disengage from the grooves in the geared section.