If you have not paid and submitted your tax return you can quit and chose to start over. If you are using any of the additional schedules you cannot use the free version of the program.
https://ttlc.intuit.com/community/taxes/discussion/how-do-i-start-over-i-had-to-quit-and-when-i-came...
check this website(different from the turbotax site) to see if you qualify for a free file.
https://freefile.intuit.com/
Disclaimer: Not a tax professional. Information gathered from internet links. Anything dated in June 2019 was posted in prior years and is before the 2019 limits and changes.