Open notepad, just copy the below code and paste it into your notepad.
shutdown -s -t 60
In the code above, 60 represent the time period in seconds after which PC will shutdown, you can change this also as specifying 60 will shutdown computer after 60 seconds that is 1 minute and if you want to shutdown it after 2 hours then you will write shutdown -s -t 7200.
Now save this file on your desktop as whatever name you want it as.bat after the file name is the must.
Now you will see a batch file on your desktop, now when you double click on the file your computer will get shut down after a specified time.