TurboTax accounts cannot be deleted.  You can clear any tax data from the account then just abandon the account.

If you have not paid for the online edition you are using, have not filed your tax return or registered the Free edition, then you can clear your return and start over. Click on Tax Tools on the left side of the program screen while working on the 2019 online tax return. Click on Clear & Start Over.

how do i delete my turbotax if i registered but did not file

You can't.  Once you've paid or registered, we're required to store copies of your return.  Read more here:  Can I delete my tax return in TurboTax Online? - Community