Sub RemoveRangeGroup( _
   ByVal startIndex As Integer, _
   ByVal count As Integer, _
   ByVal isRowGroup As Boolean _
) 

Dim instance As IRangeGroupSupport
Dim startIndex As Integer
Dim count As Integer
Dim isRowGroup As Boolean
 
instance.RemoveRangeGroup(startIndex, count, isRowGroup)

void RemoveRangeGroup( 
   int startIndex,
   int count,
   bool isRowGroup
)

fpSpread1.ActiveSheet.AddRangeGroup(0, 20, true);
fpSpread1.ActiveSheet.AddRangeGroup(0, 10, true);
fpSpread1.ActiveSheet.RangeGroupBackGroundColor = Color.Yellow;
fpSpread1.ActiveSheet.RangeGroupButtonStyle = FarPoint.Win.Spread.RangeGroupButtonStyle.Enhanced;

FarPoint.Win.Spread.IRangeGroupSupport rangeGroupSupport = ((FarPoint.Win.Spread.IRangeGroupSupport)(fpSpread1.ActiveSheet));
if ((rangeGroupSupport == null)) {
    return;
}
rangeGroupSupport.RemoveRangeGroup(0, 10, true);

FpSpread1.ActiveSheet.AddRangeGroup(0, 20, True)
FpSpread1.ActiveSheet.AddRangeGroup(0, 10, True)
FpSpread1.ActiveSheet.RangeGroupBackGroundColor = Color.Yellow
FpSpread1.ActiveSheet.RangeGroupButtonStyle = FarPoint.Win.Spread.RangeGroupButtonStyle.Enhanced

Dim rangeGroupSupport As FarPoint.Win.Spread.IRangeGroupSupport = CType(FpSpread1.ActiveSheet, FarPoint.Win.Spread.IRangeGroupSupport)
If rangeGroupSupport Is Nothing Then
   Return
End If
rangeGroupSupport.RemoveRangeGroup(0, 10, True)