Thread:Project:Support desk/Manually expiring user passwords in MW 1.23

The Release notes/1.23 states that "Admins can expire users users passwords manually..." I'm a relatively new admin - the only instructions / information I could find on how to do this was on the Manual:user table page. The manual states that the date a user's password expires (user_password_expires) can be set manually - see below:
 * "...Can also be set manually by calling User->expirePassword."

What does this mean? How do I call User->expirePassword? Is this from a terminal screen? Any additional information or examples would be helpful. I'm still fairly new to MediaWiki.

MediaWiki 1.23.1; PHP 5.4.20; MySQL 5.6.14; Private enterprise knowledge management wiki hosted on Windows 7.

-Thanks!