Allow to remove the admin from WPMU DEV Permissions

I’ve created a site on WPMU DEV Hosting with my client’s account and have created a second admin account for myself.
I would like to remove my client’s email from WPMU DEV > Permissions, so only I could access the WPMU DEV features on a site.

Out of the box, this is not possible, my client’s email can’t be removed, because the plugin “sees” that this was a user that activated it. Please consider this as a feature request, that other admins can edit the WPMU DEV Permissions and remove the “first” admin.