You have to pay the fees first with a credit card to remove Premium. In the Free Edition you might have added a state return or Plus or some other service. So you have to either delete state or pay first.
How to find your fees…
Log in to your return
Click on My Account at the top, then on Tools
Click on My Fees
A window will pop up that shows the fees
For help with fees, One of these links is how to remove Premium
https://ttlc.intuit.com/replies/3301994
