Sub ClearCustomFunctions() 

Dim instance As ICustomFunctionSupport2
 
instance.ClearCustomFunctions()

void ClearCustomFunctions()

public class CubeFunctionInfo : FarPoint.CalcEngine.FunctionInfo 
{ 
public override string Name { get { return "CUBE"; } } 
public override int MinArgs { get { return 1; } } 
public override int MaxArgs { get { return 1; } } 
public override object Evaluate (object[] args) 
{ 
double num = FarPoint.CalcEngine.CalcConvert.ToDouble(args[0]); 
return num * num * num; 
} 
} 

FarPoint.Win.Spread.Model.ICustomFunctionSupport cfs; 
cfs = (FarPoint.Win.Spread.Model.ICustomFunctionSupport)fpSpread1.ActiveSheet.Models.Data; 
cfs.AddCustomFunction(new CubeFunctionInfo()); 
fpSpread1.ActiveSheet.SetFormula(1, 1, "CUBE(4)");
FarPoint.Win.Spread.Model.ICustomFunctionSupport2 icf2;
icf2 = (FarPoint.Win.Spread.Model.ICustomFunctionSupport2)fpSpread1.ActiveSheet.Models.Data;
icf2.ClearCustomFunctions();
fpSpread1.ActiveSheet.RecalculateAll();

Public Class CubeFunctionInfo
   Inherits FarPoint.CalcEngine.FunctionInfo

   Public Overrides ReadOnly Property Name() As String
        Get
             Return "CUBE"
        End Get
   End Property

   Public Overrides ReadOnly Property MinArgs() As Integer
        Get
             Return 1
        End Get
   End Property

   Public Overrides ReadOnly Property MaxArgs() As Integer
        Get
             Return 1
        End Get
   End Property

   Public Overrides Function Evaluate(ByVal args() As Object) As Object
        Dim num As Double = FarPoint.CalcEngine.CalcConvert.ToDouble(args(0))
        Return num * num * num
   End Function
End Class


Dim cfs As FarPoint.Win.Spread.Model.ICustomFunctionSupport
cfs = FpSpread1.ActiveSheet.Models.Data
cfs.AddCustomFunction(New CubeFunctionInfo)
FpSpread1.ActiveSheet.SetFormula(1, 1, "CUBE(4)")

Dim icf2 As FarPoint.Win.Spread.Model.ICustomFunctionSupport2
icf2 = FpSpread1.ActiveSheet.Models.Data
icf2.ClearCustomFunctions()
FpSpread1.ActiveSheet.RecalculateAll()