How do I cancel everything ?

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 2020 online tax return. Click on Clear & Start Over.

TurboTax online accounts cannot be deleted.  If you are not going to use TurboTax online then just abandon the account.

What exactly are you trying to cancel?   If you have not e-filed you can just "walk away" or clear out the data if you did not register or pay.

CLEAR AND START OVER

https://ttlc.intuit.com/questions/2586254-how-do-i-clear-and-start-over

But if you actually e-filed by clicking the big orange button that said "Transmit my returns now"   it is too late.  You cannot cancel that.