I do I undo a bank reconciliation under Quickbooks Online?

Thank you for taking the time to reach out to us here on the Community page, @zawadik.

The Undo option for a reconciled period without manually editing individual transactions from the register is only available in QuickBooks Online Accountant 

Here's how:

1. In QuickBooks Online Accountant, go to your clients' list.
2. Find your customer and open their QuickBooks Online account.
3. Select the Gear icon on the Toolbar.
4. Under Tools, select Reconcile.
5. On the Reconcile an account page, select History by account.
6. On the History by account page, select the Account and Report period to locate the reconciliation to undo.
7. From the Action column drop-down list, select Undo.
8. When prompted to confirm, select Yes.
9. In the final confirmation window, select Undo.
10. Select OK.

For additional information, check out this article: Undo your client’s reconciliations with QuickBooks Online Accountant.

If you don't have the accountant version of QuickBooks, you'll need to undo the reconciled transactions one at a time. Unreconciling the transactions manually will affect your beginning bank balance. I'd suggest consulting an accountant for more expert ways of dealing with this kind of situation. Also, you may read this article for your reference.

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