Adding user accounts to a Chromebook allows multiple people to use the same Chromebook without having to share passwords. When you add an additional account to your Chromebook, the user will simply login with their Google account and be able to work and access any files that are in their Google Drive. Adding an additional user account will not remove or delete the owner account. If you are wanting to remove, delete, or change the owner account you'll need to factory reset (Powerwash) the Chromebook.