The Frenchman had only been at Elland Road for a month after he was brought to the club by former boss Gary McAllister.
New boss Simon Grayson has already signed two new defenders on loan, Richard Naylor (Ipswich) and Carl Dickinson (Stoke) and has decided Assoumani is surplus to requirements.
The 25-year-old's only appearance for the club came in last month's 3-1 defeat at MK Dons. He was an unused sub against Carlisle.