DISABLE CTRL+ALT+DEL KEYS

Open /etc/inittab file, enter:
# vi /etc/inittab
Search for line that read as follows:
ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now
And remove the line or comment out the above line by putting a hash mark (#) in front of it:
# ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now
Save the file and exit to shell promot. Reboot system to take effect or type command:
# init q