At first grub boot prompt, you have 4sec to pres: [e]


Does not matter which grub kernel you choose as we are not really modifying the kernel.

With your [e] key just choose to edit the first one

add at the end the word "single", like so:

<YTABLE=us crashkernel=auto rhgb quiet single


and press [enter]

Back at the Grub menu press [b] to boot.
When the prompt comes up we are in single user mode


In this mode we are not required to authenticate and we can go ahead and reset the password by typing at the prompt:

[[email protected] /]# passwd


retype the password to confirm and the root password has been changed,

do a shutdown by typing:

shutdown -r now