I'll provide information and steps to remove an existing bank or account feed and swap to a new one.
I suggest disconnecting the account from the Online Banking feature in QBO. Before doing this, make sure to add and match all the pending transactions. That being said, disconnecting the account will delete any transactions in the For Review tab.
Once done, please follow these steps on how to disconnect an account:
Go to Banking on the left pane, then select Banking at the top.
Choose the account you want to change, and then click Edit (pencil icon).
Click on Edit account info.
In the Account window, check the box next to Disconnect this account on save.
Also, after you've downloaded the correct transactions from your financial institution, you can review them to avoid duplicate entries and to make sure your books are accurate.