Once you've e-filed, you have to wait and see if the IRS accepts your return. If they do, there's no going back. :(
It looks like you're using the Free Edition. So you made no payment, correct? If you made payment for a product, and then e-filed your return, there will not be the option for refund.
If, by chance, the IRS rejects your e-filed return for some reason, it's as if you never filed. So at that point, you can choose not to re-submit. But again, if you already paid for some TurboTax product or feature, that cannot be refunded.
