How to hide the overflow menu option in GroupBar?

<syncfusion:GroupBar Name="myGroupBar" Height="340" ShowGripper="False"
 
Orientation="Vertical" HorizontalAlignment="Center" Width="250" 
 
Loaded="MyGroupBar_Loaded" ItemHeaderHeight="28" VisualMode="StackMode"  
 
DynamicResizing="True">
 
<!--Group Bar Item-->
 
<syncfusion:GroupBarItem Name="myitem" HeaderText="Mailbox"
 
ShowInGroupBar="True" HeaderImageSource="Images/mail.png">
 
<!--Group View-->
 
<syncfusion:GroupView>
 
<!--Group View Item-->
 
<syncfusion:GroupViewItem Name="inbox" Text="Inbox" ToolTip="Inbox"
 
TextHorizontalAlignment="Left"
 
ImageHorizontalAlignment="Right"  ImageSource="Images/Inbox.png" >
 
</syncfusion:GroupViewItem>
 
<syncfusion:GroupViewItem Text="Outbox" ToolTip="Outbox" Name="outbox"
 
TextHorizontalAlignment="Left"
 
ImageHorizontalAlignment="Right"
 
ImageSource="Images/Outbox.png" >
 
</syncfusion:GroupViewItem>
 
<syncfusion:GroupViewItem Text="Sent Items" ToolTip="Sent Items"
 
Name="sentitems" TextHorizontalAlignment="Left" ImageHorizontalAlignment="Right"
 
ImageSource="Images/sent.png">
 
</syncfusion:GroupViewItem>
 
<syncfusion:GroupViewItem Text="Spam" ToolTip="Spam" Name="spam"
 
TextHorizontalAlignment="Left"
 
ImageSource="Images/Spam.png" ImageHorizontalAlignment="Right">
 
</syncfusion:GroupViewItem>
 
<syncfusion:GroupViewItem Name="trash" Text="Trash"  ToolTip ="Trash"
 
TextVerticalAlignment="Bottom"
 
TextHorizontalAlignment="Left" ImageHorizontalAlignment="Right"
 
ImageSource="Images/trash.png" >
 
</syncfusion:GroupViewItem>
 
</syncfusion:GroupView>
 
</syncfusion:GroupBarItem>
 
<syncfusion:GroupBarItem HeaderText="Favorite Folders" Name="favorite"
 
ShowInGroupBar="True" HeaderImageSource="Images/folder.gif" >
 
</syncfusion:GroupBarItem>
 
<syncfusion:GroupBarItem HeaderText="Contacts"
 
Name="contacts" ShowInGroupBar="True" HeaderImageSource="Images/Contact.png">
 
</syncfusion:GroupBarItem>
 
<syncfusion:GroupBarItem HeaderText="Task" Name="task" ShowInGroupBar="True"
 
HeaderImageSource="Images/Tasks.png">
 
</syncfusion:GroupBarItem>
 
<syncfusion:GroupBarItem HeaderText="Notes" Name="notes" ShowInGroupBar="True"
 
HeaderImageSource="Images/Notes.png" >
 
</syncfusion:GroupBarItem>
 
</syncfusion:GroupBar>

private void MyGroupBar_Loaded(object sender, RoutedEventArgs e)
{ 
 
Menu menu = VisualUtils.FindDescendant((sender as GroupBar) as Visual, typeof(Menu)) as Menu;
 
//Hide the NavigationPane Visibility
 
menu.Visibility = Visibility.Collapsed;
 
}