You shouldn't delete bookmark in the Recently Bookmarked list.

• "Most Visited" and "Recently Bookmarked" are examples of the so called Smart Bookmarks folders and are not real existing folders.
• Such smart folders show a list created by a query of the places.sqlite database that stores the bookmarks and the history in Firefox.
• The bookmarks that show up in such smart folder listing are stored elsewhere in another folder and any changes made are applied to the real bookmark or history item.
• Such lists show a maximum of 10 entries by default and you add a new bookmark or visit a website then a new item is added at the top and the entry at the bottom disappears from that list.
• The items that are removed from the list are not gone, but merely do not show up anymore in that list.
• Any actions like copy & paste or delete that you perform on bookmarks in such a list are done on the original bookmark.

tyvm guess ill leave it be and is there any way to show more than 10 ?

You can create a new query with a higher maximum (maxResults=XX) if you want to see more entries.

Create a new bookmark, you need to copy and paste the full text starting with place: to the location field and close and restart Firefox to make the smart folder work.

Name:
Recently Bookmarked

Location:
place:folder=BOOKMARKS_MENU&folder=UNFILED_BOOKMARKS&folder=TOOLBAR&queryType=1&sort=12&excludeQueries=1&excludeItemIfParentHasAnnotation=livemark%2FfeedURI&maxResults=20