You can right click that smart bookmarks folder and select Delete to remove it.

• Deleting bookmarks

Didn't work for me. I tried right-clicking; I tried editing bookmarks and using both keyboard delete button and pulldown edit command; I tried dragging it to the trash. I don't want these taking up space for something I never use. In fact, none of them will delete or even move up or down the list. They were imported from a backup; IT forgot to transfer them when they upgraded my computer.

A possible cause is a problem with the file places.sqlite that stores the bookmarks and the history.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox