title: Removing ng-class
body: <p>How can I remove ng-class in angular js.</p>
  
  <p>Here is my example code</p>
  
  <pre><code>&lt;form name="myform" ng-class="plus"&gt;
      //...
      &lt;button ng-click="save()"&gt;click&lt;/button&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>and what I tried but does not work</p>
  
  <pre><code>$scope.add_page = function(){
      $scope.myform.removeClass(plus);//what i try but not work
  }
  </code></pre>
  
  <p>any suggest how to removed class or remove attribute ? </p>