If you want to shut the computer down instead of reboot, replace /r with /s.
If you type shutdown /?, you'll see all of the shutdown command's parameters.
Usage: shutdown [/i | /l | /s | /sg | /r | /g | /a | /p | /h | /e | /o] [/hybrid] [/soft] [/fw] [/f] [/m \\computer][/t xxx][/d [p|u:]xx:yy [/c "comment"]] No args Display help. This is the same as typing /?. /? Display help. This is the same as not typing any options. /i Display the graphical user interface (GUI). This must be the first option. /l Log off. This cannot be used with /m or /d options. /s Shutdown the computer. /sg Shutdown the computer. On the next boot, if Automatic Restart Sign-On is enabled, automatically sign in and lock last interactive user. After sign in, restart any registered applications. /r Full shutdown and restart the computer. /g Full shutdown and restart the computer. After the system is rebooted, if Automatic Restart Sign-On is enabled, automatically sign in and lock last interactive user. After sign in, restart any registered applications. /a Abort a system shutdown. This can only be used during the time-out period. Combine with /fw to clear any pending boots to firmware. /p Turn off the local computer with no time-out or warning. Can be used with /d and /f options. /h Hibernate the local computer. Can be used with the /f option. /hybrid Performs a shutdown of the computer and prepares it for fast startup. Must be used with /s option. /fw Combine with a shutdown option to cause the next boot to go to the firmware user interface. /e Document the reason for an unexpected shutdown of a computer. /o Go to the advanced boot options menu and restart the computer. Must be used with /r option. /m \\computer Specify the target computer. /t xxx Set the time-out period before shutdown to xxx seconds. The valid range is 0-315360000 (10 years), with a default of 30. If the timeout period is greater than 0, the /f parameter is implied. /c "comment" Comment on the reason for the restart or shutdown. Maximum of 512 characters allowed. /f Force running applications to close without forewarning users. The /f parameter is implied when a value greater than 0 is specified for the /t parameter. /d [p|u:]xx:yy Provide the reason for the restart or shutdown. p indicates that the restart or shutdown is planned. u indicates that the reason is user defined. If neither p nor u is specified the restart or shutdown is unplanned. xx is the major reason number (positive integer less than 256). yy is the minor reason number (positive integer less than 65536).