Thank you for reaching out to the Community. When deleting your old bank account in QuickBooks Online, it won't affect any transactions including the Reviewed tab they will still remain in your QuickBooks account. Let me walk you through on how to delete it.
Go to Settings ⚙ and choose Chart of Accounts.
Find the account you want to delete.
Under the Action ▼ drop-down view register and tap Make inactive.
When you run reports, you’ll still see inactive accounts and their transactions. You can customize some reports to hide inactive accounts, but this may affect the accuracy.