QB Issue Resolution:

Did you connect the bank in the first place?  Do you see accounts listed in the banking screen when you click banking from the side tab?

Resolution for Issue 'I need to disconnect an old bank account and add a new bank.' available: Yes (Solved).
Source: Intuit Community forum.

I need to disconnect an old bank account and add a new bank.: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for Accounts listed
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Error Recovery for Accounts listed [Canada]
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