In following the steps that I indicated you would take a copy of the DocumentTabGroupTemplateKey ControlTemplate from the DockManagerGeneric.xaml and remove the closeBtn and filesMenu and anything that references those in the template. That would leave you with something like this:

  <igDock:XamDockManager Name="xamDockManager">
   <igDock:XamDockManager.Resources>
    <ControlTemplate x:Key="{x:Static igDock:TabGroupPane.DocumentTabGroupTemplateKey}" TargetType="{x:Type igDock:TabGroupPane}">
     <DockPanel ClipToBounds="True" SnapsToDevicePixels="True" KeyboardNavigation.TabNavigation="Local">
      <DockPanel x:Name="PART_HeaderArea" Panel.ZIndex="1" DockPanel.Dock="{TemplateBinding TabStripPlacement}">
       <DockPanel>
        <Button x:Name="showNavigatorButton"
                 DockPanel.Dock="Right"
                 Visibility="Collapsed"
                 Command="{x:Static igDock:DockManagerCommands.ShowPaneNavigator}"
                 CommandParameter="{TemplateBinding igDock:XamDockManager.DockManager}"
          Style="{DynamicResource {x:Static igDock:TabGroupPane.DocumentPaneNavigatorButtonStyleKey}}"
                            />
        <ItemsPresenter x:Name="PART_TabHeaderPanel" Margin="5,2,10,0"
                 KeyboardNavigation.TabIndex="1"/>
       </DockPanel>
      </DockPanel>
      <Border x:Name="ContentPanel"
           KeyboardNavigation.TabIndex="2"
           KeyboardNavigation.TabNavigation="Local"
           KeyboardNavigation.DirectionalNavigation="Contained"
           BorderThickness="{TemplateBinding BorderThickness}"
           CornerRadius="3"
           BorderBrush="{DynamicResource {x:Static igDock:DockManagerBrushKeys.TabbedPaneOuterBorderFillKey}}"
           Background="{TemplateBinding Background}"
           Visibility="Visible"
           SnapsToDevicePixels="True" >
       <Border x:Name="InnerBorder"
               BorderThickness="1"
               CornerRadius="1"
               BorderBrush="{DynamicResource {x:Static igDock:DockManagerBrushKeys.TabbedPaneInnerBorderFillKey}}"
               SnapsToDevicePixels="True" >
        <Border x:Name="ThickInnerBorder"
               BorderThickness="2"
               BorderBrush="{DynamicResource {x:Static igDock:DockManagerBrushKeys.TabbedPaneCenterFillKey}}"
               SnapsToDevicePixels="True" >
         <Border x:Name="InnerMostBorder"
               BorderThickness="1"
               BorderBrush="{DynamicResource {x:Static igDock:DockManagerBrushKeys.TabbedPaneOuterBorderFillKey}}"
               Background="{TemplateBinding Background}"
               SnapsToDevicePixels="True" >
          <ContentPresenter ContentSource="SelectedContent"
                    Margin="{TemplateBinding Padding}"
                    x:Name="PART_SelectedContentHost"
                    SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
                    ContentTemplateSelector="{TemplateBinding SelectedContentTemplateSelector}"
                    ContentTemplate="{TemplateBinding SelectedContentTemplate}"
                    Content="{TemplateBinding SelectedContent}" />
         </Border>
        </Border>
       </Border>
      </Border>
     </DockPanel>
     <ControlTemplate.Triggers>

      <Trigger Property="igDock:XamDockManager.PaneLocation" Value="Document">
       <Setter Property="BorderThickness" Value="1" />
       <Setter Property="Padding" Value="2" />
       <Setter Property="TabStripPlacement" Value="Top" />
      </Trigger>
      <Trigger Property="TabStripPlacement" Value="Bottom">
       <Setter Property="Margin" TargetName="PART_TabHeaderPanel" Value="5,0,10,2"/>
      </Trigger>
      <Trigger Property="TabStripPlacement" Value="Left">
       <Setter Property="Margin" TargetName="PART_TabHeaderPanel" Value="2,10,0,5" />
       <Setter Property="DockPanel.Dock" TargetName="showNavigatorButton" Value="Bottom" />
      </Trigger>
      <Trigger Property="TabStripPlacement" Value="Right">
       <Setter Property="Margin" TargetName="PART_TabHeaderPanel" Value="0,5,2,10"/>
       <Setter Property="DockPanel.Dock" TargetName="showNavigatorButton" Value="Bottom" />
      </Trigger>
      <Trigger Property="IsEnabled" Value="False">
       <Setter Property="TextElement.Foreground" Value="{DynamicResource {x:Static igDock:DockManagerBrushKeys.GrayTextBrushKey}}"/>
      </Trigger>
      <!-- PaneNavigatorButtonDisplayMode -->
      <MultiDataTrigger xmlns:interop="clr-namespace:System.Windows.Interop;assembly=PresentationFramework">
       <MultiDataTrigger.Conditions>
        <Condition Binding="{Binding Source={x:Static interop:BrowserInteropHelper.IsBrowserHosted}}" Value="True" />
        <Condition Binding="{Binding Path=(igDock:XamDockManager.DockManager).PaneNavigatorButtonDisplayMode, RelativeSource={x:Static RelativeSource.Self}}" Value="WhenHostedInBrowser" />
       </MultiDataTrigger.Conditions>
       <Setter Property="Visibility" TargetName="showNavigatorButton" Value="Visible" />
      </MultiDataTrigger>
      <DataTrigger Binding="{Binding Path=(igDock:XamDockManager.DockManager).PaneNavigatorButtonDisplayMode, RelativeSource={x:Static RelativeSource.Self}}" Value="Always">
       <Setter Property="Visibility" TargetName="showNavigatorButton" Value="Visible" />
      </DataTrigger>
     </ControlTemplate.Triggers>
    </ControlTemplate>
   </igDock:XamDockManager.Resources>

Thanks Smith,

It worked, we copied   <igDock:XamDockManager.Resources> contents from your code and its working fine.

Thanks for your support.

Vivek