What are the effects of renunciation? (Negotiable Instruments Law)

The following are the effects of renunciation in favor of a secondary party or in favor of the principal debtor:

[1] A renunciation in favor of a secondary party may be made by the holder before, at or after maturity of the instrument. What is the effect of this? Such secondary party is discharged and all parties subsequent to him but the instrument itself remains in force.
[2] A renunciation in favor of the principal debtor may be effected at or after maturity. What is the effect of this? The instrument is discharged and all parties thereto provided the renunciation is made unconditionally and absolutely.

Note that, in either case, renunciation does not affect the rights of a holder in due course without notice.