Take vCenter server SSH and type reboot.
Or else you can connect to the host on which vcenter is running as VM and you can perform reboot or shutdown.
I think I have to rephrase my query, it is not about how to shutdown or reboot.
When you shutdown a system , the system brings down services in a sequence which we used to view in Linux/Unix boxes when the shutdown signal is imitated. (Typically text messages that run in the screen).
I expect something like that in Vcenter console instead of progress bar.