More than likely, it was added as part of his user entry via a SIS upload, which typically means you cannot change/override it via the UI. What you likely will need to do, is create a CSV file with his new information, and upload it via the SIS Upload feature, which should set his information the way you want it.
IE: create a "users.csv" file with only one line in it for that user's intended information, per the formatting on this page: SIS Import Format Documentation - Canvas LMS REST API Documentation
Set the "status" column as "active" and then upload it via the admin panel.
You could also likely do this via the API, but the CSV method will be the easiest if you haven't messed with the APIs before.
This discussion post is outdated and has been archived. Please use the Community question forums and official documentation for the most current and accurate information.