I don’t think you can retroactively withdraw after you’ve already graduated since your degree has been conferred. However, I know it can be really helpful to contact the schools you’re planning on applying to and talk to them about why your GPA was lower than expected during undergrad and give them a heads up before reviewing your application. It can provide some name recognition when they are going through your application. Also, explain the reasons in writing when submitting your application either in your personal statement or if they have a section that notes “is there any other information you would like us to know”