Reset the root password on Centos7

1 – Boot up and when the GRUB menu is displayed, select option to edit.

2 – Select Option to edit (e)

3 – Go to the line of Linux 16 and change ro with rw init=/sysroot/bin/sh.

4 – Now press Control+x to start on single user mode.

5 – Now access the system with this command.
chroot /sysroot

6 – Reset the password.
passwd root

7 – Update selinux information
touch /.autorelabel

8 – Exit chroot
exit

9 – Reboot your system
reboot