How do I cancel TurboTax?

[Critter]

If you have not paid or filed a return you can simply log out and let the account go dormant.   If you have already paid or registered the account it cannot be deleted.  And if you have already filed successfully the account cannot be closed or deleted. 

[VolvoGirl]

If you filed it then it is too late unless it rejects.  You can just leave and abandon it.  Or You can try to clear It.

https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-clear-and-start-over-in-turbotax-onli...