I don't have the option to clear and start over under my account button

 

Get your taxes done using TurboTax

Are you only seeing 2 options under MY ACCOUNT?   If so, then your return is not open.

When you open your return ("take me to my return"), then once you are past the blue "Simple and accurate" screen, MY ACCOUNT should have 5 options.

Also see this

FAQ:   How do I clear and start over?

https://ttlc.intuit.com/replies/4248526