Section 13(2)(vi) in The West Bengal Scheduled Castes And Scheduled Tribes (Reservation of Vacancies in Services And Posts) Act, 1976
(vi)Notwithstanding the provisions contained in paragraph (v), if, in the public interest, it is necessary to fill up any reserved vacancy remaining unfilled on account of nonavailability of a qualified Scheduled Caste or Scheduled Tribe candidate, as the case may be, the appointing authority shall refer the vacancy to the State Government for de-reservation. Upon such reference, the State Government may, if it is satisfied that it is necessary or expedient so to do, by order de-reserve the vacancy, subject to the condition that the reservation against the vacancy so de-reserved shall be carried forward against the subsequent unreserved vacancy.'.]]