You can change the password or other details of a vCenter Single Sign-On user from the vSphere Web Client. You cannot rename users in the vsphere.local domain. That means you cannot rename administrator@vsphere.local.
You can create additional users with the same privileges as administrator@vsphere.local.
vCenter Single Sign-On users are stored in the vCenter Single Sign-On vsphere.local domain.
You can review the vCenter Single Sign-On password policies from the vSphere Web Client. Log in as administrator@vsphere.local and select .