All commissioned and warrant officers of the organized militia of Washington shall be appointed and commissioned or warranted by the governor only as hereinafter provided. No person shall be so appointed and commissioned or warranted unless he or she shall be a citizen of the United States and of this state and more than eighteen years of age. Every commissioned and warranted officer shall hold office under his or her commission or warrant until he or she shall have been regularly appointed and commissioned or warranted to another rank or office, or until he or she shall have been regularly retired, discharged, dismissed or placed in the reserve.