I'm here to help and share some information regarding disconnecting an account in QuickBooks Online. Once the account is disconnected, any transactions in the For Review tab will be deleted.
See the steps below to disconnect the account:
In QuickBooks go to Banking and select the affected bank account
Select the Edit ✎ icon to the right of the bank name and select Edit account Info
In the Account box, scroll to the bottom and check Disconnect this account on save
Save and Close.
If you want to reconnect the account, here's how:
Go to your bank's website and navigate to the point where you enter your login credentials
Copy the address at the top of the page (starts with http), by highlighting the entire address and pressing Ctrl+C
In QuickBooks, go to Banking and select Add account
In the 'Enter your bank name or URL' field, paste the address copied in step 2 (above), press Enter, and try connecting again.
To learn more about disconnecting and reconnecting a direct bank feed in QuickBooks, you can go through this article: Troubleshoot issues with Bank Feeds.
The following write-ups contains more information about the direct feed feature in QuickBooks Online: