Want to delete a bookmark you don’t want anymore? Just right click on the bookmark you don’t want and select delete. This works even in the bookmarks menu.
Want to organize your bookmarks? Put them into subdirectories for efficiency? Go to the “Bookmarks” menu and select “Organize Bookmarks”. From there you can drag/drop to organize them all you want. Consider subdirectories if you have a lot of bookmarks to keep the list easy to navigate.