HI I understand cash and accrual accounting. How do I get rid of a bal on a bank a/c cash basis without affecting an accruals bank a/c balance which is correct at zero

I'd be glad to help you clear your bank balance in QuickBooks Online (QBO).

To zero out the balance, we can check your bank statement to ensure that this is an incorrect transaction. If yes, you can delete it to correct the balances in your account.

Although, I would recommend reaching out to your accountant before making any changes since this will affect your accounting records.

Here's how to delete a transaction:
 

1. Find the transactions you want to delete, and open them one at a time.
2. At the bottom of the page, click More.
3. Choose Delete.
4. Click Yes to confirm the deletion.
    

You can also read this article for more information: Void or Delete an Invoice or Other Transactions.

Once you're all set, feel free to check out these links that can guide you in seamlessly managing your transactions and accounts: 
 

• Categorize and match online bank transactions in QuickBooks Online
• Reconcile an account in QuickBooks Online

Please let me know in the comments if you have any other questions aside from working with your banking transaction in QBO. Take care and stay safe!