Flexi does create multiple important pages during activation. Those pages do not go away during uninstall or deactivation due to security reasons. So, when user re activate Flexi plugin it will re-create a pages hence there are multiple pages on page list.
You may need or wanted to remove unwanted pages from the list but unaware that which one to remove because on of the pages is linked with Flexi. If you delete that you need to go to the Flexi Settings and reassign the pages. So to make it quicker look at the GREY text just at the right side of page title started with Flexi text. This means that, it is the pages currently being used.
Simply select those pages that do not have grey text with title and delete it. You don't have to do any additional settings after then.