Remove all NTP server entries from the node config

        Returns:
            True if the operation succeeds, otherwise False.

def remove_all_servers(self):
        """Remove all NTP server entries from the node config

        Returns:
            True if the operation succeeds, otherwise False.
        """
        # 'no ntp' removes all server entries.
        # For command_builder, disable command 'ntp' gives the desired command
        cmd = self.command_builder('ntp', disable=True)
        return self.configure(cmd)