You need a user with administrator rights to shut down a computer remotely.
This method works on Windows XP, but Windows 7 can remember the user and password even after a reboot of your computer.
First, press Winkey + R, type \\nameserver, and press Enter, Windows then will ask you for the credentials. Remember to change nameserver for the name of the PC you want to shut down.
Click “Remember my credentials”, this way Windows 7 will save that user and password for the remote computer.
Now your commands will execute using that user. So let continue with the process:
Press WinKey + R, type shutdown -i, and press Enter, the next window appears:
Add the name of the computer you want to shut down, specify the action and the reason why you are doing this, and you are done.