How to reset CentOS root password with GRUB boot loader

Sometimes you may forget root password of CentOS system, which happened to me a few times with some of the development server.
Here is how to reset it.

You need to reboot the system ether by reset button or power recycle.
At the boot up GRUB screen you need to press any key to get the boot menu. By default GRUB has 5 second delay to display boot menu which is configured in "/boot/grub/menu.lst". You need to act quick.

Screen outputs:

Press any key at GRUB boot up.

Press 'e' after choosing one of the boot up kernel menu.

Select the list with "kernel /vmlinuz-" and press "e"

At the following screen, add word "single" with space after the end of existing line as shown in picture below and press "Enter"

You will get back to GRUB menu list and press "b" to boot

The system will boot up and automatically login and prompt you with shell prompt.

Then enter "passwd" to change root password and reboot the system.

You can login now with new password!