MainWindow.xaml

<syncfusion:RibbonWindow x:Class="DisableHeader.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:syncfusion="http://schemas.syncfusion.com/wpf"                 
        xmlns:local="clr-namespace:DisableHeader"                     
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <syncfusion:SfSpreadsheetRibbon syncfusion:SkinStorage.VisualStyle="Office2010Blue" />
        <syncfusion:SfSpreadsheet x:Name="spreadsheet"
                                       Grid.Row="1"
                                       FormulaBarVisibility="Visible"
                                       syncfusion:SkinStorage.VisualStyle="Office2013">
        </syncfusion:SfSpreadsheet>
    </Grid>
</syncfusion:RibbonWindow>