New York State law protects the right of tenants in privately-owned buildings to have a roommate under certain conditions. If those conditions are met, tenants do not need the permission of the landlord to have an additional occupant, and are legally allowed to have a roommate even if their lease prohibits it.
A roommate holdover case is brought to make a roommate leave the apartment or house that you share. You cannot lock your roommate out of the home you share without a court order. If you are a renter, to start a roommate holdover case, your roommate must rent from you not the landlord.
So if you want them out, since they have been there less than a year, you can give them a written 30 day notice to vacate. If they don't move out, then you can file a formal court eviction case in the local Housing Court to evict them.
Serve a ten-day notice to quit: The property owner serves the squatter with a ten-day notice to quit, informing them to vacate the property within ten days.
When only one tenant is named on a lease, the tenant has the right to take in a roommate and the roommate's dependent children. When two or more tenants are named on the lease, the number of tenants and roommates cannot exceed the number of tenants named in the lease.
To request the removal of a name from your lease, the remaining tenant(s) and the departing co-tenant should send a certified letter to the landlord. The landlord should always check that the person whose name is being removed wants to be taken off.
When only one tenant is named on a lease, the tenant has the right to take in a roommate and the roommate's dependent children. When two or more tenants are named on the lease, the number of tenants and roommates cannot exceed the number of tenants named in the lease.
If the roommate has been there more than a year but less than two years, you must give 60 days notice of the termination. If the roommate has been there more than two years, you must give 90 days notice termination.