I am trying to figure out what the Shared with us list is used for as none of our sites have content there. I would also like to remove that option in the left navigation, but when I go to Edit mode it's not listed there for me to remove.
Hello Melissa! The "Shared with us" element in the navigation is from SharePoint. It appears when you open list or library on any SharePoint site with connected group. It should provide you with access to resources shared with your group (which is bound with the SharePoint site). It does not seem possible to switch off this, at least in a simple way. Please check this discussion on a Microsoft site.