How to delete a custom view mode? I have a site that had display suite installed, but the custom view mode I'm trying to delete is not listed in the display suite admin page (admin/structure/ds/view_modes). 

So I tried disabling/uninstalling all DS modules, and that didn't seem to help. I re-installed the module and confirmed the ds_view_modes table is indeed empty. 

I know I can uncheck the checkbox to disable it for a given content type, but I want it gone completely so it doesn't cause confusion. 

In the image, you can see the extra display is called "Classified Ad"

How can I accomplish this?
Check the source code, maybe something is registering it via hook_entity_info_alter