I have a website showing the work of several artists. Each artist has their own page (they can login and edit their page). The page is generated by a Drupal View of type User. Each year there is a special event where each artist can choose to display an icon to indicate if their studio is open to the public. When the event is over I want the admin user to be able to hide all icons without editing each individual artist's page. The admin user needs to have a simple control (they are not technical enough to be able to modify the drupal view settings).
I though one way to do this would be to have a checkbox in a block or something (the admin user would toggle this checkbox as required). Then in a Global-PHP field in a view, I would access this control to hide or display the field showing the icon. I can manage the CSS and the PHP and have used Views and Global-PHP fields before but I get confused with Views relationships.
To be clear, the control only has one value across all users. Any admin user can change it, and it controls the view for all artists.