Quick Question about Add/Remove Leagues

On one of my new saves I have started up I realised after a year or so into it that I forgot to add the Turkish League to the game,however I just wanted it in there as it was a big league but have no intention of managing in it,I can't seem to find the option to change it from playable to view only,is there a way of changing the league from playable to view only once you've already started a save or is it simply only possible to do once a new save is been created?.