Accounts and User Management
System Preferences→Accounts→click on the plus sign button (+) at the lower-left of the window (requires administrator privileges)
Unix administrators might be tempted to use the
usermod commands to add, remove, and modify a
user, respectively, from the Terminal. However, those commands
don’t exist on Mac OS X.
System Preferences→Accounts→select the user’s name in the left column click on the button with a minus sign (-) to delete the user
While logged in, you can’t remove yourself from the system. If you want to remove your user account from the system, you have to log out and log back in as another user.
System Preferences→Accounts→select your username in the left column→Login Options
System Preferences→Accounts→select your username in the left column→Password
passwd command in the Terminal.
When choosing a password, you should avoid using dictionary words (i.e., common, everyday words found in the dictionary) or something that can be easily guessed. To improve your security, we recommend that you choose an alphanumeric password. Remember, passwords are case-sensitive, so you can mix upper- and lowercase letters with your password as well.
System Preferences→Accounts→Login Options→select the checkbox next to “Enable fast user switching”