I don't know how to delete from cache uploaded image. I wanna have only one image in cache storage.

<button style="width: 300px; height: 300px;"></button>
<script type="text/javascript">
  var q = document.querySelector('button')
  var i = 1;
  q.addEventListener('click', function()
  {
    q.style.backgroundImage = "url('foto/"+ i +".png')"; 
    i *= -1
  })
</script>

gif