How do I clear 2018 tax info since we had to have an accountant do that year and my information was incorrect, and was never submitted?

You could start a new account. 

The old TurboTax account will have that info, no real way to delete it unless you pretend to amend it, which might make a mess. 

Oh rats, I was hoping there was a different answer!   🙂

For your 2019 return, it will pull in 2018 information on TurboTax Online, but you can edit and delete as needed. TurboTax Online is available for the current tax year (2019) only, so it would not prepare a 2018 return. If you were using that version of the software, you are not "stuck" in 2018. It only pulls in prior information to get you started.