RedHat 6 / CentOS 6 system gives us the opportunity to reset root password in case we forget it, on condition that we have a direct access to the machine on which we want to reset root password. Password can be reset after booting the system into single-user mode.
1. Reboot the system
2. At the screen: “Booting Red Hat Enterprise Linux…” or “Booting CentOS…” press any key to display GRUB menu.