To resign a game that you are currently playing, open the game that you wish to resign and press the Resign button. 

If no one has made a move the game will be automatically resigned for you. The game will be counted as a loss for the player who failed to play.

* Smart Match - Resign after 7 days

* Match Of The Day, Playing Now, Friends, Recents and Rematches - Resign after 11 days