select2.js multiple

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/select2/3.2/select2.min.js"></script>
<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/select2/3.2/select2.css">
<form action="">
  <input type="text" value="Muda este texto antes do reset...">
  <select multiple style="width:300px;">
    <option value="AL">Alabama</option>
    <option value="Am" selected>Amalapuram</option>
    <option value="An" selected>Anakapalli</option>
    <option value="Ak">Akkayapalem</option>
    <option value="WY">Wyoming</option>
  </select>
  <button type="button">Reset</button>
</form>

CSS

* {
  padding: 0;
  margin: 0;
}

form > * {
  display: block;
  padding: 10px;
  width: 200px;
}

JavaScript

$('select').select2();
$('form').on('reset', () => {
  $(this).find('select').select2("val", "");
});
$('button').on('click', () => {
  const form = document.querySelector('form');
  form.reset();
});