Login to CentOS 7 without Login Prompt

[root@testcentos7 ~]# vi /etc/systemd/system/getty.target.wants/getty\@tty1.service 

Find the line

ExecStart=-/sbin/agetty  –noclear %I $TERM

and change to

ExecStart=-/sbin/agetty --autologin root --noclear %I $TERM

Next boot there will be no login prompt for root user

if you want to login console as root without password.change the follow file :

vim /lib/systemd/system/serial-getty@.service

Find the line

ExecStart=-/sbin/agetty --keep-baud 115200,38400,9600 %I $TERM

and change to

ExecStart=-/sbin/agetty --autologin root --keep-baud 115200,38400,9600 %I $TERM