If you need to change the Unbabel Admin, all that is required is that the new user taking on the position is assigned an admin role - see how to do that in this article - and the Access Token under the Settings Page is changed as to match that user's API Key.
Note: the new Unbabel Admin must be a Freshdesk admin of the instance and a Portal User. If the user does not have an admin role in Freshdesk, the API key won't allow for all the necessary actions to be concluded, and Unbabel will break.
We highly recommend that you double check that the changes are saved by reloading the page. Having the access token matching the Unbabel Admin's API key is fundamental.