Make sure nobody is logged in: clear the browser's cookies and web storage, load the Django admin login page again, and assert its login form (#login-form) is showing.
Examples
Given I am not logged in
Given we are not logged in
And not logged in
Given I am not logged in
And we are not logged in
Pattern
Given(/^(I am |we are )*not logged in$/, …)
Part of @webship-js/django-cms-steps (github.com/webship/django-cms-steps), a step pack for Webship-js 2.0.x.