Somehow I got hooked on an expensive TurboTax plan but don’t need it so I and to clear and start over. Will I lose access to all my documents/past returns?

No, you will not lose access to any of your prior online tax returns by clearing the 2021 tax return.

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 with a lower priced edition. 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.