how to hide RadButtonElement control in panel of type RadPanelBarGroupElement

In my application 
I  have  Telerik.WinControls.UI.RadPanelBarGroupElement 
panel called "panelCompany"  , and it has collections  of three items of type
RadButtonElement

items called 
addCompany 
deleteCompany 
updateCompany

 in  my application  ,  i prevent some users to use delete option , so hide "deleteCompany "

FormMain.deleteCompany.Visibility = Telerik.WinControls.ElementVisibility.Hidden

at this  point any thing is OK  , but when i click on panel "panelCompany " ,  the button "deleteCompany" is visible again 
what can i do to hide RadButtonElement  control forever ?