Go to the Wages and Income section of your return and scroll down until you see Business Income or Schedule C as an option. If you go deeper into that section of your return, you should see an 'untitled' Schedule C that has been started. Click the trash can icon next to it to remove it.
If this method does not work, use the instructions in the TurboTax help articles below to delete the Schedule C:
How do I view and delete forms in TurboTax Online?
How do I delete a tax form in TurboTax Desktop?