If you haven’t already, sign out of your Chromebook.
At the bottom right, select the time.
Select Sign Out.
On the Chromebook sign-in screen, select the account you want to remove.
To the right of the account name, select the Down arrow.
Select Remove Account.
In the box that appears, select Remove Account.
More Information: Remove an account from a Chromebook | Chromebook Help
Click on the clock and sign out
Drop down arrow and Remove Account
Remove Account a second time