The 'Recently Bookmarked' folder is not a real folder. It displays recent entries to make it easier to find such entries.

"Recently bookmarked" contains a different view (representation) of the same bookmark on your toolbar. Deleting a bookmark deletes it from everywhere.

What do you want to achieve actually?

In Firefox When a bookmark is deleted from other bookmarks, it deletes the bookmark for the bookmark toolbar. How can I stop this from happening?