Thank you for writing.
According to the MS RibbonBar specifications the form icon should not be visible when using application menu and should be visible when the ApplicationMenuStyle property is set to BackstageView. You can hide the icon explicitly by setting its Visibility property to Hidden:
radRibbonBar1.RibbonBarElement.IconPrimitive.Visibility = ElementVisibility.Hidden
Do not hesitate to contact us if you have further questions.
All the best,
the Telerik team