You can try to clear you return but you can not delete your account. How to delete/clear your Online return
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-clear-and-start-over-in-turbotax-onli...
You can call in and ask them to deactivate it. Contact Customer Service at
https://support.turbotax.intuit.com/contact/
