Windows - End Task:

• Press Control + Alt + Delete.
• Choose Task Manager.
• Select the application that you want to force quit.
• Right-click on it and select End task.

Note: Make sure that you have selected the correct application.

Mac - Force Quit:

• Open Activity Monitor.
• Find the process you want to end in the Process Name list.
• Click Stop in the top-left corner.
• Choose Quit Process to end the process or Force Quit to end it immediately.