N.Y. State Fin. Law § 155
The treasurer's receipt, countersigned by the comptroller, setting forth that the whole sum secured by the mortgage held by the state has been paid, shall be a sufficient discharge of the mortgage, and the officer in whose office such mortgage is recorded shall record such receipt as a satisfaction of the mortgage and satisfy the mortgage of record. When any part or subdivision of any lot mortgaged to or purchased from the state, for which a separate account has been opened, is paid, the comptroller shall execute a discharge of such part or subdivision from such mortgage.
If a map and survey of the whole lot is filed with the comptroller showing particularly a part or subdivision for which no separate account has been opened, and the owner thereof pays into the treasury its full proportion of principal and interest unpaid, and satisfactory proof is furnished the comptroller that the residue of the lot is sufficient security for the sum remaining unpaid, he may execute a like discharge of such part or subdivision.
The comptroller may cancel and discharge any mortgage, on satisfactory proof that the moneys loaned and secured by such mortgage have been fully paid to the officers authorized by law to receive the same if the mortgage remains uncancelled and undischarged of record.
N.Y. State Fin. Law § 155