1. At the boot loader menu, use the arrow keys to highlight the installation you want to edit and type [A] to enter into append mode.
2. You are presented with a prompt that looks similar to the following: grub append> ro root=LABEL=/
3. Press the Spacebar once to add a blank space, then add the word single to tell GRUB to boot into single-user Linux mode. The result should look like the following: ro root=LABEL=/ single
4. Press [Enter] and GRUB will boot single-user Linux mode. After it finishes loading, you will be presented with a shell prompt similar to the following: sh-2.05b#
5. You can now change the root password by typing passwd root You will be asked to re-type the password for verification. Once you are finished, the password will be changed. You can then reboot by typing reboot at the prompt; then you can log in to root as you normally would.