Unfortunately, there is no way to downgrade a TurboTax return. You would need to create a new return to go back to the original product. 

To start a new return, select “Start a New Return” from under “My Returns” in the top left corner. Once you have started your new return, you can select “View All Returns” from under “My Accounts & Returns”. Then delete the unwanted return by clicking the small Trash Can next to it or “Delete” under the return’s name.

Honestly, as a first-time Turbo tax user I was having such a good experience until this point.
I was lulled into a sense of false safety when I clicked the Self-employment thing because of the message that said I didn't have to pay now but could review at the end. Otherwise, I could have stopped and restarted at that point. And I get it as a sales tactic but I don't like it. Thank you for letting me know. 

This is completely unacceptable