What is this 'Unsorted Bookmarks' Folder?
Chicanery! Nope, the Unsorted Bookmarks folder is a feature of Firefox, and is not a feature of Xmarks. It is related to the start icon that you see in your address bar. When you click the star icon once, the page you are currently on gets bookmarks and placed in the “Unsorted Bookmarks” folder.
You can delete unwanted bookmark folders in your browser’s bookmark manager or go to my.xmarks.com to manage.
Learn how to make Firefox save bookmarks to the Bookmark Menu instead of the Unsorted Bookmark Folder here.