How do you exit full screen on Google Windows 10?

just press esc to exit the fullscreen mode or else press alt+tab which will let you to choose another opened window. after choosing the other opened right click on the window which works in full mode and close it from there

Hit F11 to enter or exit fullscreen mode.

In some browsers (e.g. Firefox 16 for Mac), you can move your cursor to the top of the fullscreen and a menu bar will appear at top with a box in the corner to reduce from fullscreen