Try this...
I could not find Inbox.com when I checked all the programs in the Control Panel, and neither was it listed in All Programs or in the Extensions in Chrome. What I finally tried about 30 minutes ago (and hopefully it will work) was in the very last part of your reply. I went to Settings, then to Search, and there I found "Manage Search Engines" and when I clicked on that, there it was, along with the Google search engine and several more. I right-clicked on it and had an option to delete, which I clicked on, and just part of it went away. There was a "close" or big X on the right side of the box and when I clicked on that, it was gone!