Can't Delete Csv File

im creating a csv file from sql querry, after that im sending this csv file with email, after i sent the mail i wanna delete the csv file but it says 'its using by another....this is my export csv function

Function ExportCsv() Dim filePath As String = "C:FULLWorkcsvlimit_dosya.csv" Dim delimiter As String = ";" Dim sb As New StringBuilder() For i As Integer = 0 To DataGridView1.Rows.Count - 1 Dim array As String() = New String(DataGridView1.Columns.Count - 1) {} If i.Equals(0) Then For j As Integer = 0 To DataGridView1.Columns.Count -

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