Remove header by its name

		:param header_name: name of header to remove
		:return: None

def remove_headers(self, header_name):
		""" Remove header by its name

		:param header_name: name of header to remove
		:return: None
		"""
		if self.__ro_flag:
			raise RuntimeError('ro')
		header_name = self.normalize_name(header_name)
		if header_name in self.__headers.keys():
			self.__headers.pop(header_name)