The following VBA example deletes all cusp nodes in the curve.
Sub Test()
Dim s As Shape
Dim n As Node
Dim i As Long, Num As Long
Set s = ActiveShape
If s.Type <> cdrCurveShape Then Exit Sub
Num = s.Curve.Nodes.Count
i = 1
While i <= Num
Set n = s.Curve.Nodes(i)
If n.Type = cdrCuspNode Then
If n.SubPath.Nodes.Count = 2 Then
' Deleting a node from a segment containing only 2 nodes
' will remove the whole segment. If we are deleting the last
' node of the subpath, then we must move one more step back.
If n.SubPath.EndNode Is n Then i = i - 1
n.Delete
Num = Num - 2
i = i - 1
Else
' Just delete the node and adjust the number of nodes left.
n.Delete
Num = Num - 1
i = i - 1
End If
End If
i = i + 1
Wend
End Sub