As students use a Chromebook, their user profile remains on the device.  To clear the profile from the Chromebook follow these steps.


  1. On the Chromebook sign-in screen, select the profile you want to remove.
  2. Next to the profile name, select the Down arrow .
  3. Select Remove this user.
  4. In the box that appears, select Remove this user.


When you remove an account, it’s only removed from the Chromebook. The Google Account itself, including its data and settings, will still exist. 


Source:

https://support.google.com/chromebook/answer/1059260?hl=en