Login with Amazon/Amazon Pay – No Log Out Button

I activated the Log In With Amazon option in Amazon Pay, and there is no log out button. Once a customer logs in, they cannot log out. When they are logged in, Amazon Pay is the only checkout option and they are forced to pay with Amazon. They could open a new browser tab, log out of their Amazon account, come back to the website, refresh the page, then start the checkout process again, but this is obviously not tenable.