title: How to reset the date field when form is cleared
body: <p>I have a form with a date field.  Initially, the date field is empty. When the user selects a date and then clicks the clear button, the input data stays there.</p>
  
  <p>I tried date=null and undefined but didnt work</p>
  
  <p>ts</p>
  
  <pre><code>private clearValues(row: RecordDto) {
    row.Date= null
    row.contactName = null
  }
  </code></pre>
  
  <p>html</p>
  
  <pre><code>&lt;ng-container matColumnDef="Date" &gt;
      &lt;div class="date-picker-container" &gt;
        &lt;input class="date-picker form-control" ngx-mydatepicker
               (dateChanged)="onDueDateUpdate($event, row)"
               [options]="datePickerOptions" #dueDatePicker="ngx-mydatepicker"
               [errorStateMatcher]="matcher"
               [appRequiredIf]="selection.isSelected(row)"/&gt;
        &lt;button type="button" mat-button class="button-calendar"
                (click)="dueDatePicker.toggleCalendar()"
                [disabled]="row.taskName.notApplicable"&gt;&lt;/button&gt;
      &lt;/div&gt;
    &lt;/mat-form-field&gt;
  &lt;/td&gt;
  &lt;/ng-container&gt;
  </code></pre>