title: Angular 4 Form Control Removing Validation/Errors
body: <p>I have a form control that I am dynamically setting validators and removing validators. Which is fine, however -- all my form controls are marked as status invalid when I try to remove and set.</p>
  
  <p>My code for removing:</p>
  
  <pre><code>this.answerControlArr[pvqQuestionId - 1].clearValidators();
  this.answerControlArr[pvqQuestionId - 1].updateValueAndValidity();
  </code></pre>
  
  <p>My code for setting:</p>
  
  <pre><code>this.answerControlArr[pvqQuestionId - 1].setValidators(Validators.compose([Validators.required, Validators.minLength(4)]));
  this.answerControlArr[pvqQuestionId - 1].updateValueAndValidity();
  </code></pre>
  
  <p>When I print to the console, I see in the browser that the errors are still there and the status is marked as invalid? I have also tried using before setting validators:</p>
  
  <pre><code>this.answerControlArr[pvqQuestionId - 1].reset();
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/52qVX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/52qVX.png" alt="enter image description here"></a></p>