title: remove form control dynamically in angular 2 reactive forms
body: <p>Try to remove a control that I add to a form</p>
  
  <p>I have tried <code>this.*FormArray*.splice</code> but it doesn't compile. Saying that <code>FormArray has no method splice</code>. Then I tried <code>removeAt()</code> but then when I run the code the error says, <code>removeAt is not a method</code>. One compile time fails, the next runtime fails. </p>
  
  <p>I want to remove a control from an array of controls.</p>