In New York state how long does the landlord have to hold the personal property of a former tenant?

Is this question a continuation of your other threads dealing with your children or is this a new subject?

Generally 30 days after a written notice that the belongings will be disposed of.

Yes once out they left 5 boxes of stuff here

So send them a letter stating that if they do not come pick up the stuff within 30 days it will be disposed of.