title: Uncheck radio button in Angular 6
body: <p>I have a questionnaire with several radio buttons like this:</p>
  
  <pre><code>&lt;mat-radio-group name="questionA" [(ngModel)]="model.questionA"&gt;
   &lt;mat-radio-button *ngFor="let ans of answers" [value]="ans.value"&gt;
     {{ans.display}}
   &lt;/mat-radio-button&gt;
  &lt;/mat-radio-group&gt;
  </code></pre>
  
  <p>What I want is to be able to uncheck the selected radio when I make a click in it.</p>
  
  <p>I have tried this: <a href="https://stackblitz.com/edit/angular-bootstrap4-rpslys" rel="nofollow noreferrer">https://stackblitz.com/edit/angular-bootstrap4-rpslys</a> that I've forked from <a href="https://stackoverflow.com/questions/55005641/how-to-uncheck-a-radio-button-on-its-second-click-angular-2">this answer</a>. But I can't make it work in my case.</p>
  
  <p>Any help will be deeply appreciated.</p>