The instrument creating any public trust may be amended, or the trust may be terminated, by agreement of the trustee, or, if there is more than one (1) trustee, then of all of the trustees, and of the authority having the power of acceptance of beneficial interest thereunder. However, no such amendment or termination shall be effective while there exist any contractual obligations chargeable against the trust estate or its revenues unless the holder of the contractual obligations also agrees thereto.