如何删除UWP离子标题栏箭头？

<Page
    x:Class="YourAppName.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:YourAppName"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <!-- 页面内容 -->
    </Grid>
    
    <!-- 标题栏定义 -->
    <Page.TopAppBar>
        <CommandBar>
            <!-- 标题栏按钮 -->
        </CommandBar>
    </Page.TopAppBar>
</Page>

<Page.TopAppBar>
    <CommandBar>
        <CommandBar.PrimaryCommands>
            <!-- 返回按钮定义 -->
        </CommandBar.PrimaryCommands>
    </CommandBar>
</Page.TopAppBar>

<Page.TopAppBar>
    <CommandBar>
        <CommandBar.PrimaryCommands>
            <!--<AppBarButton Icon="Back" Label="Back" Click="OnBackButtonClicked" />-->
        </CommandBar.PrimaryCommands>
    </CommandBar>
</Page.TopAppBar>