Hello, @ZG10.

Good to see you here in the Community. I can help walk you through on how to cleared a transaction in QuickBooks Online (QBO). 

Since the expense account still shows as uncleared in the Chart of Accounts (COA), you have an option to change the status to cleared, and it will remain the customer's account on 0.

Here's how:

1. In the left tab, select Banking.
2. Click Go to Register.
3. From the Register Name drop-down menu, select the expense account and click OK.
4. Find the transaction that needs to be cleared.
5. To highlight click on the transaction.
6. Click on the top line of the transaction in the field between the Deposit and Payment amount.
7. On the blank field, you can continually click the field to display a C (cleared).
8. Click Save and respond to any further questions accordingly.

You can check this article for additional reference on how to change the transaction status: How do I clear, unclear, reconcile or unreconcile transactions?. 

For future reference, you can also visit this article to learn more on about reconciliation: How to reconcile accounts. 

That should do it! Feel free to leave a comment below if you have additional questions about the transaction status. I'd be happy to answer them for you. Have a good one.