I would be cautious with erasing bookmarks on a computer and then rely on Sync to restore them as the opposite can happen and the bookmarks on the Sync server might be removed as well if you reconnect, so at least make to create a backup of the bookmarks on other connected devices. Firefox keeps backups of the bookmarks in the bookmarkbackups folder, so you can check if you have a backup with these bookmarks. *Bookmarks -> Show All Bookmarks -> Import & Backup -> Restore *https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them The name of an automatically created JSON bookmarks backup in the bookmarkbackups folder includes a total item count (folders and separators included) and an hash value to prevent saving the same backup more than once.<br>You also see this count in the Restore menu drop-down list. *bookmarks-YYYY-MM-DD_<item count>_<hash>.jsonlz4.