2017 New York Laws
GOB - General Obligations
Article 15 - Modification and Discharge of Obligations
Title 3 - Requirements for Effectiveness or Enforceability of Modification or Discharge
15-301 - When Written Agreement or Other Instrument Cannot Be Changed by Oral Executory Agreement, or Discharged or Terminated by Oral Executory Agreement or O

 15-301. When written agreement or other instrument cannot be changed
  by  oral  executory  agreement,  or  discharged  or  terminated  by oral
  executory agreement or oral consent or by  oral  notice.  1.  A  written
  agreement  or other written instrument which contains a provision to the
  effect that it cannot  be  changed  orally,  cannot  be  changed  by  an
  executory  agreement  unless  such executory agreement is in writing and
  signed by the party against whom enforcement of the change is sought  or
  by his agent.
2.  A  written  agreement or other written instrument which contains a
  provision to the effect that it cannot be terminated orally,  cannot  be
  discharged  by an executory agreement unless such executory agreement is
  in writing and signed by the  party  against  whom  enforcement  of  the
  discharge is sought, or by his agent, and cannot be terminated by mutual
  consent  unless  such  termination is effected by an executed accord and
  satisfaction other than the substitution of one executory  contract  for
  another,  or  is evidenced by a writing signed by the party against whom
  it is sought to enforce the termination, or by his agent.
3. a. A discharge or partial discharge of obligations under a  written
  agreement  or  other  written instrument is a change of the agreement or
  instrument for the purpose of subdivision one of this section and is not
  a discharge or termination for the purpose of  subdivision  two,  unless
  all   executory  obligations  under  the  agreement  or  instrument  are
  discharged or terminated.
b. A discharge or termination of all  executory  obligations  under  a
  written  agreement  or  other  written  instrument  is  a  discharge  or
  termination for the purpose  of  subdivision  two  even  though  accrued
  obligations  remaining  unperformed  at  the  date  of  the discharge or
  termination are not affected by it.
c. If a written agreement or other  written  instrument  containing  a
  provision  that  it  cannot  be  terminated  orally  also  provides  for
  termination or  discharge  on  notice  by  one  or  either  party,  both
  subdivision  two  and  subdivision four of this section apply whether or
  not the agreement or  other  instrument  states  specifically  that  the
  notice must be in writing.
4.  If  a  written  agreement  or  other written instrument contains a
  provision for termination or discharge  on  written  notice  by  one  or
  either  party,  the requirement that such notice be in writing cannot be
  waived except by a writing signed by the party against whom  enforcement
  of the waiver is sought or by his agent.
5.  If  executed  by an agent, any agreement, evidence of termination,
  notice of termination or waiver, required  by  this  section  to  be  in
  writing,  which  affects  or  relates  to  real  property or an interest
  therein as defined in section 5-101 in any manner stated in subdivisions
  one or two of section 5-703 of this chapter shall be  void  unless  such
  agent was thereunto authorized in writing.
6.  As  used in this section the term "agreement" includes promise and
  undertaking.