N.Y. Real Prop. Acts. Law § 421

§ 421. Powers of attorney to be filed and registered. Before any\nperson can convey, charge, incumber or otherwise deal with any\nregistered property, or any estate, right or interest therein, as\nattorney in fact for another, the deed or instrument empowering him so\nto act shall be filed with the registrar and a memorial thereof shall be\nentered upon the certificate in the title book, in like manner as in the\ncase of a charge or incumbrance. A revocation of such power of attorney\nmay be registered in like manner as such power of attorney was\nregistered.\n