Short of retiring, footballers aren't able to suddenly terminate their contract of employment with an agreed notice period.
The complex issues surrounding their image rights & value to the company (not to mention the initial investment in acquiring the player's rights) make it impossible for a valuable player to leave their club without their club's consent. Unless they are able to enact the
Webster Ruling If Toure was to use the Webster ruling in April 2014, he'd likely need to pay the club around £22.4m in wages due - along with a percentage of his initial transfer fee.