Remove key value pair in a local or global namespace.

def remove(self, key, glob=False):
        """Remove key value pair in a local or global namespace."""
        ns = self.namespace(key, glob)
        try:
            self.keyring.delete_password(ns, key)
        except PasswordDeleteError:  # OSX and gnome have no delete method 
            self.set(key, '', glob)