Legal Question in Real Estate Law in New York

There is nothing that would prevent you from withdrawing your offer.

Ditto. Send the seller and broker a certified letter stating that your offer to purchase is withdrawn. If you wrote an earnest money check that has not cleared, stop payment on it. If the check has cleared, include a demand for refund of the earnest money. If they don't refund the deposit, you can file and foreclose a lien against the property, though with the property under water, you may have trouble collecting.

I have not seen the contract or read its language on this subject. Unless there is something that specifically states time for closing can be extended, the general rules apply and above authors are correct.