How can I deal with illegal resignation?

After reinstatement fresh resignation is must to relieve staff. He can not be relieved on the basis any resignation or offer submitted before his reinstatement. Any letter or offer or permission to resign submitted on the date when one is not in service due to illegal orders of compulsory retirement can not be treated as resignation as one was not in service on the date of such letter. Relieving on the basis of resignation that was rejected in writing is totally illegal.