Edit the grub boot loader configuration file
# vim /etc/grub.conf
After the hiddenmenu type password=newpassword then save & reboot
Example :
hiddenmenu[Here we have to type]
Password = redhat [any Password]
Stop the Menu bar Press ‘Space bar’.
Now press ‘p’ for password,Password: redhat [any password]
Now press ‘e’ for editing mode,Press Escape & Enter for booting.
Encrypt the password for security reasons:
Open two terminal,For generate a encryption password just type grub-md5-crypt
Select & Copy the encrypted password & in terminal-1
Edit the grub configuration file from terminal-2,Paste the password in password prompt, like... vim /etc/grub.conf