How can I reset the password of the email accounts under my custom domain?

I am the admin of http://theclunkerjunker.com. We use Outlook.com under a custom domain for email.  I have a user who needs their email password reset but I don't see the option to do so from the domains control panel.

Is there a way to do this with Outlook? If not, what options do I have for someone who can't log into their account?