TurboTax Free Edition is free as long as you file a 1040EZ (or 1040A
with the standard
deduction) and don't select any add-ons or
upgrades.
However, you can downgrade using
the Clear
and Start Over feature but bear in mind
that the different TurboTax "flavors" handle different tax
situations and their associated forms.
Please see FAQ (click
on see entire answer), and complete the steps to downgrade: https://ttlc.intuit.com/replies/3288495