There are a few links that discuss or describe how to re-set mac admin password,
with & without the system install-restore DVD media of the present running system.
{Note the link below from wisc.edu as it says a few things of importance; & is
likely an easier way if you can get original install series Install media. The later
10.5 installer may not work in old Panther or Jaguar systems; it's too new.}
Some of these I'd already bookmarked several years ago; and used a few back in
the day. Several of my Macs still run PPC processor (pre-intel G4) & am familiar...
This document explains how to reset a forgotten account password in Mac OS X
for ... to startup from a CD or DVD. ... System Administrator ...
https://kb.wisc.edu/page.php?id=3853
Five Ways to Reset a Lost Administrator Password... allowing the administrator pass
word to be reset by the Apple ID... how-tos/macbook-password-resetting-without ...
https://tidbits.com/article/14437
Reset a Lost Password in Mac ... If you don't have a CD or DVD handy you
can still reset your ... Any other way of getting into my system, without ...
osxdaily.com/2010/02/21/reset-a-lost-password-in-mac
{Of these ideas some involve use of 'Command Line' to back-door access Mac X
which can be similar to Terminal. Some aren't comfortable using Command Line.}
Other similar ideas appear in this type of search:
https://duckduckgo.com/?q=reset+mac+admin+password+without+system+DVD&t=ffsb&ia=web
Good luck & happy computing! 🙂