You can use the NET USE command to authenticate on the remote server and then use shutdown.exe
NET USE \\MyServer\IPC$ mypassword /USER:myuser
http://www.squidworks.net/2011/07/how-to-pass-a-username-and-password-to-windows-shutdown-exe-command/
This does not work with UAC enabled, unless the policy LocalAccountTokenFilterPolicy is enabled on the remote server.
When a user who is a member of the local administrators group on the target remote computer establishes a remote administrative connection by using the net use * \remotecomputer\Share$ command, for example, they will not connect as a full administrator. The user has no elevation potential on the remote computer, and the user cannot perform administrative tasks.