To reset a chrome book to factory (termed "powerwash" by google) settings, google has a fairly detailed walkthrough on the process linked here:[br]
[link|https://support.google.com/chromebook/answer/183084?hl=en|https://support.google.com/chromebook/answer/183084?hl=en]
You typically access this by accessing the boot menu with ***Ctrl*** + ***Alt*** + ***Shift*** + ***r*** and select the PowerWash option.
This will erase all the data and reset the device to a "out of box" state similar to when you first set it up.