Fingolfin vs Sauron

[Beren87]

Didn't Tolkien state that no one could willingly destroy it?

But Figolfin had gone off the deep end at this point. If we're assuming he was in the same mental state that he was in when he went to do battle with Melkor, than that isn't what I would call sane. So I'm not sure he would necessarily be knowing what he was doing, he'd just be following Elrond's instructions (assuming he's taken the place of Isildur here).