How to reset the root passwd if we forget the root password in red hat

Boot from the single user mode, from GRUB, do the following from the GRUB menu screen:

1. Select the desired kernel.

2. Press the 'e' key to edit that entry.

3. Use the arrow keys to navigate to the kernel line
(for example: kernel /vmlinuz-2.6.x-x ro root=/dev/hdx2)

4. Press the 'e' key to edit the line.

5. Add the argument 'single' to the end of the line and
press return.

6. Press the 'b' key to boot.

then at the prompt use passwd to reset the password.