How can I reset my quickbooks online account to how it was before I changed anything

If you are using QBO Simple Start or your account > 60 days old, you should open a new blank account and cancel the old one.

https://quickbooks.grsm.io/US

https://quickbooks.grsm.io/us-promo

Then utilize the trial version for a backup restore app if required.

https://rewindio.grsm.io/quickbooks