You may withdraw any motion you have made simply by alerting the clerk, the opposition and making a record that you've withdrawn it (usually a motion to withdraw) so the court understands your position.
In the case of In re Marriage of Garrett, 336 Ill.App.3d 1018 (5th Dist. 2003) the court did an inquiry into the income of the former husband and determined that he didn't meet the burden to qualify for a downward deviation from the child support statutory guidelines, so Section 5/505(a)(2) did not apply. That court further determined that there had been a substantial change in circumstances which required an increase in child support for the parties’ minor child. The court said that "A court may increase the amount of child support on a Motion to Modify solely on the basis of a parent’s increased ability to pay."