Mozilla Firefox - Can't edit or delete bookmarks on bookmarks toolbar.

Try fixing up your places.sqlite file. Instructions are here.

It says,

"Places database file

You can also fix this by forcing Firefox to rebuild the Places database, as follows:

1. (Optional) Export your bookmarks to an HTML file named bookmarks.html (see Exporting bookmarks to an HTML file for detailed instructions) and place the bookmarks.html file in the Firefox profile folder. If a bookmarks.html file already exists, allow the exported file to replace it.
2. From the menu at the top of the Firefox windowbar, select FileFirefox and then select the ExitQuit FirefoxQuit menu item.
3. Open the Firefox profile folder and delete (or rename) the places.sqlite file and, if it exists, places.sqlite-journal.
4. (Optional) If you want Firefox to automatically import your bookmarks from an existing bookmarks.html file in the profile folder, instead of from a JSON backup, open the bookmarkbackups folder and remove all bookmarks-(date).json files to another location.
5. It is probably a good idea to also delete (or rename) the localstore.rdf to remove the references to the old Places file but you will need to add back any toolbar customizations.

Firefox will create a new places.sqlite file and automatically import the most recent bookmark backup file. If no JSON backup is found, Firefox will automatically import your bookmarks from the profile folder bookmarks.html file, if it exists."