How to disable CTRL + ALT + DEL hotkey in Linux

Login as a root :

1. Edit /etc/inittab file
   vi /etc/inittab
   
2. Locate following entry into /etc/inittab
   ca::ctrlaltdel:/sbin/shutdown -t3 -r now
   
3. Put # at the beging of this line. Save the changes by pressing Esc :wq!