If the system is trying to upgrade you, you have a tax situation that requires a different version of TurboTax. Some common reasons are retirement savings contributions and student loan interest. You can find more information here:
https://ttlc.intuit.com/questions/2575733-why-do-i-have-to-upgrade-from-free-edition
If you want to start your return over, you can do so using these instructions:
https://ttlc.intuit.com/questions/2586254-how-do-i-clear-and-start-over-in-turbotax-online