Switching WPMU Account in Live Environment

Good day,
We have a WordPress multisite environment that is running active sites at the moment with WPMU plugins active as well.
However, the active WPMU account is a now lapsed account from one of our team members. I just opened a new WPMU account with the proper info and card, and now I need to switch accounts.
How can I most painlessly switch the WPMU account to the new account instead of the old one, ideally without having to re-install and re-configure WPMU plugins as fast as I can for the sites that are live.

Hope that makes sense!

Thanks!