Wow, I hope you didn't' do that recently "Online" for 2016...the 2016 software shut down last November.
But maybe you are just asking about starting 2017 over..
No, I did it for 2017 through the app..now I can't find a way to restart it amd start from scratch..
Need to start over in the TurboTax Mobile App? You can't do that in the app, but you can in the online version.
@TurboTaxMichaelDC provided the process.
But don't know if it can be done from the APP...or whether you have to log in to Online from a computer...thru the browser login to do it. (the "App" is just a second front end for the Browser-based Online software)
Even then, if you get to a certain stage....you may not be able to clear, and just need edit everything you mis-entered.
In TurboTax Online, you can erase your return and start from scratch as long as you haven't submitted payment, deducted the TurboTax fee from your refund, or registered.
After your entries have been cleared out, we'll prompt you to select a TurboTax product so you can start over from the very beginning.
If you're signed in under last year's login, we'll automatically transfer last year's info over if you select the PLUS upgrade, Deluxe, Premier, or Self-Employed. Federal Free Edition (without PLUS) does not include the year-over-year transfer feature.
If you can't Clear & Start Over after you've registered, and it's convenient, consider opening a new account under a new username. Up to 5 accounts can be tied to the same email address.
Here’s how:
Otherwise, try to post another question about your problem and someone should be able to help you fix it.