|There is a Mac Windows-Remote-Desktop app (free)|
This will require the windows PC is remote accessible and the login-user has elevated priveledges
If the "Shutdown" button/option is not available in the GUI, a shutdown command can de issued from the CMD-window
If the Windows-PC has telnet-server or SSH-server activated, a telenet/SSH session can be opened (user with Admin rights) from the MAC computer and issue the shutdown command.
message edited by sluc