OneStream Administrator Native User

The Administrator user is the only user that exists at the initial install and creation of your OneStream environment.  A random password generator is used to generate a long, complex password for this user, which is then stored in an encrypted vault. OneStream Support uses this ID when you open a support case and grant them permission for troubleshooting or upgrades.

You can change the password or disable this user, but it is not recommended.  If you need to do so, reach out to OS support.

Also, this user name is unaffected by inactivity thresholds and password expiration requirements that prevent users from logging in after a specific period elapses or being forced to change their password. And, it cannot be deleted. This is the one user who can always manage artifacts, data, and tools within an environment. 

The Administrators group is similar.   It is there by default, along with Everyone and Nobody.  You can add people to Administrators group, but you cannot change it's properties.  In a sense to protect you from locking yourself out.  If you did not have a system admin group, you could potentially make security changes to which you could prevent even admins from doing certain things.