(1) When the holder of a bill at or after its maturity absolutely and unconditionally renounces his rights against the acceptor the bill is discharged. The renunciation must be in writing, unless the bill is delivered up to the acceptor.
(2) The liabilities of any party to a bill may in like manner be renounced by the holder before, at, or after its maturity; but nothing in this section shall affect the rights of a holder in due course without notice of the renunciation.