If you wish to leave a game, you can tap on the three horizontal stripes on the top right corner of your screen. Next, tap on the red ‘Back to Home’ button and then tap ‘Yes’ to leave the game. Leaving a game will result in the loss of XP and Coins.
Keep in mind that Klaverjassen is a team based game and that leaving will replace you with a robot. This forces your teammate to continue on alone, assisted by a robot.
The game also uses a leave game percentage, which will go up once a player leaves a game. The percentage is visible to other player.