I have this same question but from a different angle. I am currently the one getting the email notifications as users register for events and I would like to change it so that someone else receives that email (the new site administrator). I have updated these locations in the Events Manager plugin:
Events>Settings>Event Submission Forms --updated "Guest Default User" to administrator
Events>Settings>Email Settings --updated "Notification sender address" to administrator
Events>Settings>Booking Email Templates --updated "Default contact person" and "Email events admin" to administrator
I also have the email address in the General Settings set to the administrator.
What is overriding all of these settings?