Recover or reset local login information managed by the Devise gem

I recently inherited a small Ruby on Rails platform that was more or less abandoned by its previous developer. It uses the Devise gem for user authentication/management/privileges. I have the administrative login for the live version of the platform online, but I don't know the administrative login if I just run the server locally via bin/rails server. I can't get into contact with the previous web developer.

My question is, how do I gain administrative privileges via the Devise gem when I don't have the administrative login for the local version of the application? Is there a way to reset the users managed by the Devise gem or add a new user with administrative privileges without knowing the login information of a current administrator? I need to be able to easily view pages that are only visible to users with elevated privileges without having to do a full deploy and then inspect the changes online.