Powering down or restarting an ESX server can be done in a couple of ways.
Either via the Virtual Server or Infrastructure Client interface by Right Mouse Clicking the ESX server you wish to power down (see below):
or by logging onto the ESX console with ‘root’ and running one of the following commands:
Via Command Line
Shut Down ESX
shutdown -h now – Immediately begins to shut down ESX and ‘Halt’ it.
shutdown -r now – Immediately begins to shut down ESX and then ‘Restarts’ it
init 6 – as above