Can I void entire reconciliation. I reconciled bank statement using 2019 instead of 2018.

Yes, you can "Undo" a prior account reconciliation very easily in QBO. Go-to "Reports", "Reconciliation Reports" and select "Undo"

Hello, @lindak1119.

Thanks for reaching out to the Community. I'll be happy to explain how to undo a reconciliation.

To undo a reconciliation, you must open the client's company file from QuickBooks Online Accountant, then open the account, locate the reconciliation, and undo it.

The steps:

1. In QuickBooks Online Accountant, select the client from the drop-down list on the Toolbelt to open the client's company file.

2. Select the Gear icon on the Toolbar.

3. Under Tools, select Reconcile.

4. On the Reconcile an account page, select History by account.
5. On the History by account page, select the Account and Report period to locate the reconciliation to undo.
6. From the Action column drop-down list, select Undo.
7. When prompted to confirm, select Yes.
8. In the final confirmation window, select Undo.

9. Select Ok.

For more information on Undoing reconciliations, click here.

Please keep me posted on your results with this here, the Community has you covered. Thanks again, I'll be standing by for your response.