How do I un-reconcile a bank statement

I'll share with you the two options to un-reconcile a bank statement in QuickBooks Online (QBO), @Liz01. 

If your accountant isn't connected to your QBO account, let's go to the Account History page. From there, you can manually un-reconcile each transaction from a completed reconciliation. As a reference, I'd suggest printing a reconciliation report before performing the steps below. 

1. Go to Accounting from the left menu.
2. Select Chart of Accounts.
3. Locate the appropriate bank account.
4. Choose Account history from the Action column. 
5. Select the transaction. 
6. Go to the Check (/) column and click the box many times until it is blank. 
7. Hit Save. 
8. Repeat the process for the other transactions within the reconciliation period. 

The screenshot below shows you the fifth to seventh steps. For the detailed instructions, see Step 2 through this article: Undo And Remove Transactions From Reconciliations.

Once done, make any necessary changes using the reconciliation report. Then, reconcile the account again. It's already balanced if the difference is zero. 

If your accountant is connected to your QBO company, I'd recommend getting in touch with them. They have a specialized tool to undo the entire reconciliation so you can make any changes. Also, they can help you review all your transactions to ensure your books are accurate. 

Moreover, I recommend visiting this resource hub: Reconcile Workflow. It contains in-depth details about starting, fixing any differences, and completing the reconciliation process. Just click the links beside QuickBooks Online. 

Keep me posted whenever you need help. Take care always, @Liz01.