You're not sending your password properly. The syntax for the mysqladmin command is:
mysqladmin [options] commands
Options begin with a - sign, so in your example, "password" and "abcdef" are interpreted as commands.
Type "mysqladmin" by itself on the commandline to get a list of options. You should see that you need either -p or --password= to specify a password on the commandline.
A note about security, though: If you're on a shared system, NEVER NEVER NEVER NEVER run an application by entering your password on the commandline. Any user that can view a process list will see your password as one of the options passed to the application you're running. This is easier to do on a linux/unix server than Windows, but you should be aware of it.