unable to delete managed user account

You could always try Netinfo Manager.app, in /Applications/Utilities/, unlock the lock, select users, select the user account you want to delete, and select Edit->Delete. Be very careful and don't delete any user account that doesn't have a 50x uId (user identification) number or you could really screw things up. If you have any doubts, don't do anything—I'm not responsible for any screw-ups. See http://docs.info.apple.com/article.html?path=Mac/10.4/en/mh1550.html for Apple's warning.

G4 450 MP Gigabit 1.5 GB RAM Mac OS X (10.4.10)

When I open my Netinfo manager, I find various users beside my other user accounts. Could you explain why there are such bizzare names in the 'users' section?
I bought the system brand new and have been the only user since.

Potash,
That is another matter and you should make a fresh post. If what i say doesn't settle it do that. The 'funny ' users are system processes. Since the OS is fundamentally a multi-user OS the system operates to make a user with certain facilities and restrictions for various system processes. That is why you have users like "nobody" and the rest

Robert,
actually I did want to erase my other user accounts and I found this forum then I went thru the steps you suggested but I got to the whole netinfo manager thing after all. my concern as you said is all these weird users "jabber" "nobody" "unknown" , and that is why they are there¿

should I delete 'em all?
if I delete my user name, will I lose saved files?

Thank you

Log into the admin account. If you have Fast User Switching enabled, turn it off, also disable auto login. Now try to select the managed account.

Very strange behavior, indeed. Next step is to launch Disk Utility, select the boot volume, and repair permissions, quit Disk Utility, log out and back into the admin account, and try again.

Thanks for the feedback. Good computing.