Hi Brian,
The option to show or disable sidebars on specific pages is located in the Page Attributes section that appears on the right side while editing a page. Look for the Template setting and click Edit to show the sidebar options available for that page.
Pages will use the Global Settings configured in the Customizer by default but changing the selection there will alter the sidebar display for the page you are editing.
Please let us know if there is anything else that we can do to help!