Removes a menu item from the pop-up menu.
BOOL RemoveSubItem(
   int nIndex 
);
Parameters
- [in] nIndex
 Specifies the zero-based index of the menu item that you want to remove.
Return Value
TRUE if the specified item has been removed successfully; otherwise FALSE if nIndex is negative or exceeds the number of menu items in the pop-up menu.
Requirements
Header: afxribbonbutton.h