The proper way to shutdown is to use the shutdown command.
For Example:
sudo shutdown -P now
shutdown [OPTION]… TIME [MESSAGE]
-h Requests that the system be either halted or powered off after it has been brought down, with the choice as to which left up to the system.
-H Requests that the system be halted after it has been brought down.
-P Requests that the system be powered off after it has been brought down.