N.Y.C. Admin. Code § 3-242: § 3-242 Termination of domestic partnership.

a. If either party or both parties to a registered domestic partnership determines that the partnership has terminated, one of the partners shall file a termination statement with the city clerk. The person filing the termination statement shall declare that the domestic partnership is terminated and, if the termination statement has not been signed by both domestic partners, that the other domestic partner has been notified of such termination by registered mail, return receipt requested.

b. A domestic partnership shall terminate whenever one of the parties to the partnership marries.