Section 249-A. Waiver of counsel

A minor who is a subject of a juvenile
  delinquency or  person  in  need  of  supervision  proceeding  shall  be
  presumed  to  lack  the  requisite  knowledge  and maturity to waive the
  appointment of a law guardian.  This presumption may  be  rebutted  only
  after a law guardian has been appointed and the court determines after a
  hearing  at  which  the  law  guardian appears and participates and upon
  clear and convincing evidence that (a) the minor understands the  nature
  of the charges, the possible dispositional alternatives and the possible
  defenses to the charges, (b) the minor possesses the maturity, knowledge
  and intelligence necessary to conduct his own defense, and (c) waiver is
  in the best interest of the minor.