I'd be glad to provide you the steps to disable the option for tax code when uploading your bank transactions. You can choose the No VAT option on your Account and Settings section.
Once done, you can follow the steps in the following article in uploading your bank transactions: Manually upload transactions into QuickBooks Online.
Additionally, I'm adding these helpful articles to help you manage your bank transactions:
Feel free to drop me a reply below if you need more help with importing or anything tax code related to QuickBooks Online. I'll be around to lend you a hand.