In some circumstances, you may need to revoke the access to your Monzo account. Unfortunately, Monzo don't have a guide to do so.
You should be able to navigate to this section of the Monzo app by using the following link
This should as you if you want to open the Monzo application, and should take you to the correct location of the application to revoke access. From here, slide the access to the left to display the remove access field.
Once revoked, you can readd your Monzo account to reestablish the link between Money Dashboard and Monzo.