HOW DO I UNDO MY LAST AMERICAN EXPRESS RECONCILIATION?

It is a pleasure to welcome you to the Community space, @rcharnock. I will share essential information to help you undo a reconciled transaction or account in QuickBooks Online (QBO).

Please know that users in QBO can only unreconcile a transaction manually. Thus, the option to undo an entire reconciliation isn't one of the features they can utilize to rectify the action. If you wish to undo a reconciled transaction, these are the steps:

1. Access your QuickBooks company.
2. On the left navigational bar, go to Transactions and select Chart of accounts.
3. Find the account holding the transaction. Then select Account history.
4. Select the transaction you want to unreconcile to expand the view.
5. Review the check column. If the transaction is reconciled, you’ll see an R.
6. Select the checkbox. This changes the letter in the box. Keep selecting it until the box is blank. This removes the transaction from the reconciliation.
7. Click Save and then close the account history.

I'm adding a screenshot below for visual reference.

For more details, please see this page: Undo or remove transactions from reconciliations in QuickBooks Online.

Also, I highly recommend working with an accountant if you aim to undo the entire previous reconciliation. They can streamline this task for you with just a few clicks. In case you don't have an accountant, I'm here to assist you in finding one. Just check out this page: Find a QuickBooks ProAdvisor.

On top of that, you can check out this handy article to help fix previously reconciled account in QBO: Fix issues for accounts you've reconciled in the past in QuickBooks Online.

I'll be here if you have more questions about reconciliation or need further assistance with the process I described. You can use the comment section below, and I'll respond and offer my support. Take care.