Michael got rid of himself. He said he'd sign a new deal and never. Liverpool fans aren't too fond of him for it either and he actualy got booed by some fans on his return to Anfield. His contract ran down and the club who made Michael Owen got next to nothing for him, 8 million which in "soccer" is peanuts for a player of Owens calibre.
Can't say I feel sorry for him either having been shipped out of Madrid and is now stuck up in lovely Newcastle and falling apart with injuries. He could have come back too if he'd have been patient, but his priorities, again, weren't with Liverpool.