Making menu width moving marks(small red triangle)

Making menu width moving marks(small red triangle)

I want to make clicked menu arrow(width :after), but i want  only one who is clicked turns into toggleclass(menuarrow1)  and all other back to : after

How to  make this?

$(document).ready(function(){
    $('.myMenu ul li.has-children > a').click(function() {
      $(this).parent().siblings().find('ul').slideUp();
      $(this).next('ul').stop(true, false, true).slideToggle();
$(this).toggleClass('menuarrow1');
      return false;
    });
    
}); 
        

http://codepen.io/psairidas/pen/wGpxgq


P.S. Sorry for my bad english.