What do you mean by initial petition / application?
If you mean initial I-130 and I-485 that got you conditional green card, they're decided. You got immigration benefit. You cannot erase your ex-spouse sponsors name from I-130.
Did you file I-751, Petition to Remove conditions yet? Was this a joint petition you filed with ex-spouse? If yes, then yes, you need to amend petition to Divorce Waiver petition.