VB.net how to disable column header download - vb.net

Question

Problem : I'm loading a csv file to dgv. There is a predefined column name that i set by UI design. Whenever i download this CSV file after loading into the dgv, it download the header repeatedly. Below is 2 photos.
Before download and After Clicking download 2times
Here is my download button code
Private Sub btnDownload_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDownload.Click
Dim oldFile As System.IO.FileInfo = New IO.FileInfo(filePath)
oldFile.Delete()
Dim headers = (From header As DataGridViewColumn In gridData.Columns.Cast(Of DataGridViewColumn)() _
Select header.HeaderText).ToArray
Dim rows = From row As DataGridViewRow In gridData.Rows.Cast(Of DataGridViewRow)() _
Where Not row.IsNewRow _
Select Array.ConvertAll(row.Cells.Cast(Of DataGridViewCell).ToArray, Function(c) If(c.Value IsNot Nothing, c.Value.ToString, ""))
Using sw As New IO.StreamWriter(filePath)
sw.WriteLine(String.Join(",", headers))
For Each r In rows
sw.WriteLine(String.Join(",", r))
Next
End Using
Process.Start(filePath)
End Sub
How can i stop this repeated header downloading?
Here is the upload csv file code:
Private Sub ReadCSV()
gridData.Rows.Clear()
Dim TextLine As String = ""
Dim SplitLine() As String
If System.IO.File.Exists(filePath) = True Then
Using objReader As New System.IO.StreamReader(filePath, Encoding.ASCII)
Do While objReader.Peek() <> -1
TextLine = objReader.ReadLine()
SplitLine = Split(TextLine, ",")
gridData.Rows.Add(SplitLine)
Loop
End Using
Else
MsgBox("File Does Not Exist")
End If
End Sub