However, Google mentioned in the email sent to the user, this feature will be deprecated:
Since we launched the beta version of 'Chrome Supervisor Users' four years ago, there have been significant changes in how Chrome and your users are using computing devices.
We've learned a lot over the past four years and listened to feedback on how to improve the user and kids experience.
Based on these feedbacks, we decided to create a brand new Chrome OS Parental Control feature that is expected to be pushed to right-needed families later this year.
Starting January 12, 2018 (this Friday), users will no longer be able to create or re-import supervisory accounts. However, existing users can continue using the current settings on their Chromebook, Winddows, Mac, and Linux computers.
In addition, starting from January 15,Chrome.com/ManageThis web version of remote management features will no longer be available. This means that parents can not change their existing browsing restrictions for children during a function window.
Of course, as a temporary alternative, Google recommends parents to migrate to the latest release last September "Family LinkParental Control Solutions.
This service allows parents to create a Google Account for their children and then manage their browsing history on Android for Android. Unfortunately, the program is only for mobile devices, while Chrome "supervising users" is for the desktop.