If the user has the same login email for all Boardable accounts, they are able to toggle between various board accounts.
To do this, go to the left-hand side beneath the org logo (if one is uploaded), select "switch accounts," and a drop-down list of the all board accounts associated with that login email will appear.
Note this is also where one goes if wishing to create another Boardable account for a separate organization. If you would like to sign up a new account for a free trial, select "Create New Organization."