WPF: Remove the title/control box

Well, try this

WindowStyle="none"

like this:

<Window x:Class="Test.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow"  WindowStyle="None"
    MinHeight="350" MaxHeight="350" MinWidth="525" MaxWidth="525">
<Grid>

</Grid>
</Window>

Edit:

It looks a little stupid but this way (with Min- and MaxHeight/Width at the same size) you can prevent the window from beeing resized

This is an alternative way of doing it. To remove the Max-/minimize you need to change the ResizeMode like this

<Window x:Class="MyWpfApplication.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="" Height="350" Width="525" ResizeMode="NoResize">
    <Grid>

    </Grid>
</Window>

After that you can remove the Close button by adding this ( read more here )

private const int GWL_STYLE = -16;
private const int WS_SYSMENU = 0x80000;
[DllImport("user32.dll", SetLastError = true)]
private static extern int GetWindowLong(IntPtr hWnd, int nIndex);
[DllImport("user32.dll")]
private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

public MainWindow()
{
    SourceInitialized += Window_SourceInitialized;
}

void Window_SourceInitialized(object sender, EventArgs e)
{
    var hwnd = new WindowInteropHelper(this).Handle;
    SetWindowLong(hwnd, GWL_STYLE, GetWindowLong(hwnd, GWL_STYLE) & ~WS_SYSMENU);
}