You can easily change Spend Management account owners. 

To change the email associated with your Spend Management account, the account owner must update the business information within the U.S. Bank Online Banking Dashboard. For more information on how to do this, see: How do I update my business profile?

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Changing the email address associated with the Spend Management account will also change the email used for logging in and receiving alerts and communications. Once you save these changes and log out, the old email will no longer be accepted when logging in.