' When your end user clicks on the track, a new thumb will be added at that location.
Private Sub xamNumericRangeSlider_TrackClick(ByVal sender As System.Object, ByVal e As TrackClickEventArgs(Of System.Double))
   ' When your end user clicks on the track, a new thumb will be added at that location.
   ' Define new thumb
   Dim thumb As xamSliderNumericThumb = New xamSliderNumericThumb
   'Set the thumb's value to the area where your end user clicked
   thumb.Value = e.Value
   'Add to the Slider's Thumbs collection
   Me.xamNumericRangeSlider1.Thumbs.Add(thumb)
   ' Set the thumb to be active
   Me.xamNumericRangeSlider1.ActiveThumb = thumb
End Sub
' When your end user clicks on the Button, the current active thumb will be deleted
Private Sub Button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
   ' Ensure there is an active thumb
   If (Not (Me.xamNumericRangeSlider1.ActiveThumb) Is Nothing) Then
      ' Remove the active thumb from the Slider's Thumbs collection
      Me.xamNumericRangeSlider1.Thumbs.Remove(Me.xamNumericRangeSlider1.ActiveThumb)
   End If
End Sub