I misentered Parent's social security number wrong on Form 8615. Is there a way to go back and change this?

If your are using a TurboTax Desktop product,  you can try switching to forms mode to edit the actual Form 8615.

To switch to Forms Mode in TurboTax Desktop, you can:

1. Click on "Desktop," in the top right of your TurboTax screen In you left panel scroll down to Form 8915 and click on it
2. Form 8615 will appear in your right panel
3. In your right panel edit your parents Social Security number.

If you are preparing your parents tax return, the information should flow from the personal information section to the form.  If you need to enter their Social Security number for their tax return, you can go back to the "Personal Info" tab and select "Edit" by your parents name(s).