My sister lives with my mother in n.y.s. for free for years no lease
She is unstable and my mother wants her out of the house.
Notice to vacate??
Eviction?
Is there a form that does not use the term non payment of rent?
Thank you

I'm a landlord in NYS. General Eviction Information for New York (http://www.lawny.org/index.php/housing-self-help-141/housing-and-eviction-self-help-142/48-general-eviction-information)

The forms are available in office supply stores in my area - have you checked your area?