When you create such bookmarks, place them in a temporary folder in the Bookmarks Manager. Then just open that folder and delete everything.

Open the Bookmarks Manager, press the Alt or F10 key bring up the tool bar, and select Bookmarks. Hot key is <Control>(Mac:<Command>) <Shift> B.

Select the first you want to remove. Then, holding down the <Control> key, select the rest. After, right click one of the selected, select Delete.

You can delete the places.sqlite file to remove all the bookmarks.

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

See also:

• https://support.mozilla.org/kb/restore-bookmarks-from-backup-or-move-them
• http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox