Certain setting on your Chromebook can only be edited by the owner account. The account with which you first sign in will be automatically set as the owner account.
The owner rights can not be transferred to another account. This way you will have to reset your Chromebook back to factory settings by conducting a ‘Powerwash’, in order to change the owner account (see the part ‘How do I reset my Chromebook to factory settings). Keep in mind all data and accounts will be erased from your Chromebook when conducting a powerwash. After you have reset your Chromebook to it’s factory settings, you can restart your Chromebook and sign in with the desired owner account.