Let me help you so you can have this done in no time, SOCCERMALL.
If you disconnect, QuickBooks will remove transactions in the For Review tab. If these transactions are over 90 days old, you'll not be able to download them into QuickBooks again. Here are the steps to disconnect an account from online banking:
Navigate to Transactions, then Bank Transactions.
Choose the tile for the bank account.
Click on the pencil icon, then select Edit account info.
Check the box that says Disconnect this account on save.
However, if you encounter an error and attempt to disconnect the bank from QuickBooks to resolve the connection issue, I advise not doing so at this time. Please inform us of the error message you received first, as this will help me identify the appropriate solution. You can also provide your bank's name so I can check my resources here.
The articles below guide when reviewing and reconciling your accounts in QuickBooks.