Section 415 of Indian Companies Act 2013 "Acting President and Chairperson of Tribunal or Appellate Tribunal"
(1) In the event of the occurrence of any vacancy in the office of the President or the Chairperson by reason of his death, resignation or otherwise, the senior-most Member shall act as the President or the Chairperson, as the case may be, until the date on which a new President or Chairperson appointed in accordance with the provisions of this Act to fill such vacancy enters upon his office.
(2) When the President or the Chairperson is unable to discharge his functions owing to absence, illness or any other cause, the senior-most Member shall discharge the functions of the President or the Chairperson, as the case may be, until the date on which the President or the Chairperson resumes his duties.
Section 416 of Indian Companies Act 2013 "Resignation of Members"
The President, the Chairperson or any Member may, by notice in writing under his hand addressed to the Central Government, resign from his office:
Provided that the President, the Chairperson, or the Member shall continue to hold office until the expiry of three months from the date of receipt of such notice by the Central Government or until a person duly appointed as his successor enters upon his office or until the expiry of his term of office, whichever is earliest.