From time to time, passwords are lost or forgotten - even root's password. One way of removing the root password is to boot to single user mode from an installation cdrom. Mount the root, /, partition and blank out the encrypted password field in the shadow file. Here's an illustration.
ok boot cdrom -s
# mount /dev/dsk/c0t0d0s0 /mnt
# more /mnt/etc/shadow
root:9Zpah2q.zd.JJu:13832::::::
daemon:NP:6445::::::
bin:NP:6445::::::
sys:NP:6445::::::
adm:NP:6445::::::
lp:NP:6445::::::
uucp:NP:6445::::::
...
# vi /mnt/etc/shadow
root:BLANK THIS FIELD OUT:13832::::::
daemon:NP:6445::::::
bin:NP:6445::::::
sys:NP:6445::::::
adm:NP:6445::::::
lp:NP:6445::::::
uucp:NP:6445::::::
...
:wq!
# cd /
# umount /mnt
# reboot -- -s
Change the root password in single user mode (don't need to add "root" but I do it for clarification.
# passwd root
passwd: Changing password for root
New password:
Re-enter new password:
passwd (SYSTEM): passwd successfully changed for root