If you don't submit the I-864 (Affidavit of Support), which will be due at the time of filing I-485 or DS-230, the case cannot proceed to completion.
Otherwise, even after submitting the I-864 you can still withdraw an approved I-130, anytime until the very last minute before the green card is approved (although if you wait until the last minute, they might approve the green card before processing your withdrawal request).
PD: Jan 2003 (EB3 rest of world)
I-485 Approved: July 2007
I am a layman, not a lawyer. What I write here is not official or professional legal advice. In addition, my answers on this forum are specific to the scenarios discussed in each thread and should not be generalized to other situations.