If your building is now a single-family home, you’ll need to remove it from the HPD records. Buildings with tenants are required to register annually with the department. If you are in their records and do not complete an annual registration, there is a fine associated.
You can send the form to the:
Property Registration Assistance Unit
100 Gold Street, Section 6E
New York, NY 10038
If you need more information, contact the borough hall office of your particular borough.