Why can't I unbind my button???

I used to be able to, by replacing a hotkey with another button in use. But then, one random day, I was no longer able to. If a button would be empty, it's setting them to the default button. I don't want this. I want it completely unbound. I don't want to bind all these things to keys I won't press. I just want them empty, holy crapppp...

Is this for anyone else too?