Are you using the Online version? If you haven't filed, registered or paid you can try to clear and start over
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-clear-and-start-over-in-turbotax-onli...
Or if it doesn't let you clear and you haven't paid and filed you could just start a new account. Online is only good for 1 return per account. But you can use the same email address for 5 accounts
