Are you using the "Library" dialog? You can open that using either: * Command+Shift+b * "Show All Bookmarks" on the Bookmarks menu I'm a Windows user, so on my platform, after selecting either Bookmarks Menu or Bookmarks Toolbar, I can delete bookmarks from the list on the right side using either: * right-click > Delete * click to select > Delete key on the keyboard Do either of those work on Mac? ---- Or is the problem that your changes get lost after you Quit out of Firefox and start it up again?