Thanks for getting back to us, @Sstoro.

Before deleting the payment transaction, we'll need to remove it first from the deposit account.

Here's how:

1. Go to the Accounting menu, and then choose the Chart of Accounts.
2. Choose the account you want to run, and then select View register. This will let you view all the sales receipts and payments connected to the deposit.
3. From there, remove the checkmark from payments you want to delete. This will remove the transactions from the deposit.
4. Click Save once done.

You can identify if the transaction was already reconciled if it has the letter R in the Reconciliation box before making changes. Make sure you add it back in order not to encounter any errors the next time you reconcile.

I'm also adding here some resources that you can check out about managing sales transactions in QBO for future reference: 

• How to edit a sales transaction form
• View sales transactions

Don't hesitate to drop a comment below if you have other questions. I'm more than happy to help. Take care!