Any person committed to the custody of the Mississippi State Hospital or the East Mississippi Hospital may, notwithstanding the terms of any order of commitment, be permitted by the medical director or his authorized agent, to go at large on probation and without custody or restraint for such time and under such conditions as such medical director shall judge best. All persons committed to the custody of the Mississippi State Hospital or the East Mississippi State Hospital may be discharged by the director pursuant to its regulations, notwithstanding the terms of any order of commitment.