We added a user before to use for ourselves, but I never really went into how to change your password or delete a user, or a lot of other things you can do.

To change your full username, use chfn -f newusername. You can change the other information you added too, just do a manual lookup to get them (man chfn).

You can change your password by using the passwd command. You'll have to put your old password in first, unless you're root, and then your new one.

You can also delete a user, using deluser usertodelete. Obviously, don't go deleting your own user.