SOURCE

$(function(){
   setTimeout(function(){
     $('.a').css('overflow', 'hidden !important');
$('.b').css('overflow', 'hidden !important');
  $(document.body).css('overflow', 'hidden !important');
   },1100)

})

<div class='a'>
  <h2>2</h2>  <h2>2</h2>
  <h2>2</h2>

  <div class="b">
      <h2>2</h2>
  <h2>2</h2>
  <h2>2</h2>
  <h2>2</h2>

  </div>
</div>

.a{
  width: 200px;
  height: 200px;
  background-color: red;
  overflow-y: auto;
}

.b{
  width: 200px;
  height: 100px;
  background-color: blue;
  overflow-y: auto;
}