Contact Labour (Regulation and Abolition) Act, 1970
4 [5. Resignation
(1) A member of the Board , not being an ex officio member ,may resign his office by a letter in writing addressed to the Central Government.
(2) The office of such a member shall fall vacant from the date on which his resignation is accepted by the Central Government, or on the expiry of thirty days from the date of receipt of the letter of resignation by that Government whichever is earlier.]