Thanks for following up with the Community, Andrew. I have information for you to undo a bank reconciliation in QuickBooks Online (QBO).
To begin with, you can undo reconciled transactions one at a time. But if you'drather start fresh, it's best to get in touch with your accountant. They can use their QuickBooks Online Accountant (QBOA) to reverse the reconciliation. To invite them, you can follow these steps:
Open your QBO account.
Go to the Gear icon in the upper-right of your screen, and select Manage Users.
From the Accounting Firms tab, click the Invite button.