fderStr2 = System.Text.RegularExpressions.Regex.Replace(fderStr1, "^([^s]*)\(", "")

其實只要一句就可以了，表示式為替換（ 括號之前的所有東西
fderStr2 = System.Text.RegularExpressions.Regex.Replace(fderStr1, "^([^s]*)\(", "")

關於正則表示式的使用
Dim xRegex As New System.Text.RegularExpressions.Regex(1)
括號裡的1 改成 0 也一樣的，目前不知道是什麼作用，但必須得填
fderStr2 = xRegex.Replace(fderStr1, "^([^s]*)\(", "")

替換三個引數，
Dim xRegex As New System.Text.RegularExpressions.Regex(1)
fderStr2 = xRegex.Replace(fderStr1, "^([^s]*)\(", "")
會報警告，改成下面的，不會報
fderStr2 = System.Text.RegularExpressions.Regex.Replace(fderStr1, "^([^s]*)\(", "")

        If Label5.Text <> "Label5" And Label6.Text <> "" And Label5.Text <> ""
 
 Then
            Dim xRegex As New System.Text.RegularExpressions.Regex(1)
            Dim fder1Path, fder2Path, fder3Path, fderStr1, fderStr2, fderStr3, fderStr4 As String
            fder1Path = Trim(Label5.Text)
            fder2Path = Trim(Label6.Text)
            fder3Path = Trim(Label7.Text)
            
 
Dim dir As New System.IO.DirectoryInfo(fder1Path)
            For Each d As System.IO.DirectoryInfo In dir.GetDirectories
                ' Dim finfo As New System.IO.FileInfo(d.Name)
                'If (finfo.Attributes And System.IO.FileAttributes.Hidden) <> System.IO.FileAttributes.Hidden Then
                'End If
                fderStr1 = d.Name
                ' fderStr2 = System.Text.RegularExpressions.Regex("^([^s]*)\(", "")
                fderStr2 = xRegex.Replace(fderStr1, "^([^s]*)\(", "")
                MsgBox(fderStr2)
            Next
        Else
            MsgBox("請 選擇 三個資料夾", MsgBoxStyle.Exclamation, "提示")
        End If