You might be familiar shutting down a windows machine remotely from other windows machine,  if you want to do it from your linux box it pretty much same as you do it in windows. Here we use net rpc shutdown command to do it.

Before proceeding check if command is installed or not as shown below.
[root@mygw ~]# net rpc shutdown --help
Usage:
net rpc shutdown
    Shut down a remote RPC server

currently its installed on my machine so its showing usage and description for the command, if it is not on your machine it will give message like not found or not installed. If it is not installed  install samba-common package  as shown below.

CentOS
[root@centos ~]# yum install samba-common
Ubunut
root@ubuntu:~# apt-get install samba-common
Shutting down remote PC :
root@ubuntu:~# net rpc shutdown -I 192.168.10.10 -U username%password

Shutdown of remote machine succeeded
gil ...