Earnings of offenders who reside in the center and work in the community shall be collected by the chief probation officer. From such earnings the chief probation officer may pay the offender’s board and personal expenses and such administrative costs as are allocable to him. Any balance may be paid periodically to the offender as deemed appropriate by the chief probation officer. Upon the offender’s release from juvenile court wardship or termination of his probation, all funds credited to his account shall be paid to him.