To quit the game, choose File > Quit, press Ctrl+Q, or click the 'X' in the top right corner of the window (Windows).
If there is a game with unsaved changes currently in progress, you will be asked if you want to save the game before quitting. To save, click Yes (if the match has not been previously saved and you Cancel out of the resulting dialog box, the program will not quit and your current unsaved game will be unaffected). To discard any unsaved changes and quit immediately, click No. To stay with your current unsaved game and not quit, click Cancel.
If there are no unsaved changes to the current game, you will simply be asked to confirm. Click Yes to quit, or No to cancel.