How to delete Safari history ?

I can see the "clear history" box, but when I click on it, nothing happens, because it is not selectable.

I also tried this: Command all > right click > delete, but it does not delete. Instead it just reverts to highlighting one line. I right click on that one line > delete , but to no avail.

I also tried this: Command all > drag to trash bin , but that doesn't work either.

I wonder if I need to change some settings on the computer ?

I wonder if there are analysts who have prevented me from deleting my browsing history so that they can track my browsing history ?

This problem started after I tried to download youtube videos using a third party site.

I have exhausted my various options. Now I have stopped using Safari, instead I use Opera. I can delete browsing history on Opera but not on safari. That's weird.