How to force an app to close on your iPhone, iPad, or iPod touch. You can even force the Finder to quit, if it stops responding: Select Finder in the Force Quit window, then click Relaunch. Then select the app in the Force Quit window and click Force Quit. (This is similar to pressing Control-Alt-Delete on a PC.).

Or choose Force Quit from the Apple menu  in the upper-left corner of your screen. Press these three keys together: Option, Command, and Esc (Escape). Not into keyboard shortcuts? How to force an app to quit If the window is open, it will close after hitting that keystroke combination. Hitting Command+Option+W will close all windows in the currently active Mac application, or the Finder of Mac OS X. Now, press the Option/Alt key on your Mac keyboard. With the app/Finder open, click on File from the top menu. Note that this method works for all Finder Windows or multiple instances/windows of other apps (including browsers etc). How to Close all Windows in Mac App with Keystroke+Click.

If the app doesn't quit, follow these steps to force the app to quit. To quit (close) a Mac app normally, choose Quit from the app's menu in the menu bar, or press Command (⌘)-Q.

Close all windows on mac shortcut