N.J. Stat. Ann. § 43:10-5.8

4. Any retirant or beneficiary who is eligible to receive an adjustment to a pension under the provisions of this act may, at any time, waive the right thereto by filing a written notice of waiver with the pension commission. Such waiver may be withdrawn at any time and upon such withdrawal the adjustment in the pension shall commence with the pension payment for the next following month.