I choose premium filing by mistake. I meant to use the free filing
See this TurboTax support FAQ for how to downgrade using the online editions - https://ttlc.intuit.com/turbotax-support/en-us/help-article/change-service-level/downgrade-lower-priced-version-turbotax-online/L2IDaMvkt_US_en_US?uid=m9j0dqz7