Choose the Logout Page for Salesforce Users

Direct users to a specific logout destination that maintains your own branding experience after they log out of Salesforce. Or, send them to a specific authentication provider’s page.
Available in: Group, Professional, Enterprise, Unlimited, Performance, and Developer Editions

From Setup, go to Security Controls > Session Settings. Set the Logout Page Settings to provide the URL of the custom logout page. If none is provided, the default is unless MyDomain is enabled. If My Domain is enabled, the default is