How can I delete some I don't or hardly EVER use?I can't speak for OTHERS but I have no idea what line the OP is referring to.  What is the "Most visited line"?Ditto...The line I'm referring to is on Firefox, yahoo home page, all across the screen, at the top under the back arrow, the little house, under the box showing which website is up, showing a few of my most visited sites.
I want to delete some of the ones I never use. Clear as MUD?I believe you are referring to the Bookmarks TOOLBAR.  You should be able to right-click on then and select delete to remove any you don't want.Right on Strollin...worked like a charmIf it is history, simply select (but don't click), mouse-over, and hot the delete key.
You can also go to your bookmarks, right-click on the site and there and select, 'Forget About This Site'; that you remove all traces of the website from your history.
You can get there by Bookmarks>SHOW All Bookmarks> and select 'History' which should be the very top.