cat /etc/inittab 

# inittab is no longer used when using systemd.

#

# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.

#

# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target

#

# systemd uses ‘targets‘ instead of runlevels. By default, there are two main targets:

#

# multi-user.target: analogous to runlevel 3

# graphical.target: analogous to runlevel 5

#

# To view current default target, run:

# systemctl get-default

#

# To set a default target, run:

# systemctl set-default TARGET.target

ll /usr/lib/systemd/system/ctrl-alt-del.target

lrwxrwxrwx. 1 root root 13 Apr 12 23:42 /usr/lib/systemd/system/ctrl-alt-del.target -> reboot.target

rm /usr/lib/systemd/system/ctrl-alt-del.target 

init q

如需开启则重新创建链接，再次执行init q重新reload配置文件即可。

centos关闭ctrl+alt+del重启