Click the red close button in the top-left corner of the window
Press Command + W to close the current window
Press Command + Q to quit the app and close all its windows
Right-click the app icon in the Dock and choose Quit
Use File > Close Window from the menu bar
Use the keyboard shortcut Option + Command + W to close all windows in the current app
Press Control + Command + Q to lock the screen if needed to leave windows open but exit quickly