Root password recovery in CentOS
Find the line that starts with:
linux16 /vmlinuz...
At the end of that line, add the following:
rd.break
Press Ctrl + X
Remount the Filesystem as Read/Write
mount -o remount,rw /sysroot
Chroot into the Real System
chroot /sysroot
Change the Root Password
passwd
Re-label SELinux Contexts (important)
touch /.autorelabel
exit and reboot