If a program freezes, crashes, or stops responding on your macOS operating system, you can follow the steps below.
Force stop with key combination
Press Option(Alt) + Command+ESC (Escape) on your keyboard or select “force quit” from the menu in the upper left corner.
A window will open which is listing running applications. You must confirm by selecting the program you want to force quit from this list.
If you fail to force the program to quit with this method, you may need to restart your computer. Restart your computer by selecting “Restart..” from the menu.