秀丸で開いて 置換で

 \t を なしに
(\tの後に半角空白(空白の数は とりあえず ひとつで なくなるまで 繰り返し実行する)
(なし というのは 何も 入れない状態)

正規表現にﾁｪｯｸを入れて
置換では ﾀﾞﾒですか？

複数ﾌｧｲﾙの場合は､grepして置換というのを使えばいいでしょう｡

ｺﾒﾝﾄいただいたように｢ﾃﾞｰﾀはﾀﾌﾞ区切り｣で作り直してみました｡
お試しください｡

Option Explicit

'行を列に分離
Function splitRow2Col(sour As String)
 Dim i As Integer, ln As Integer, num As Integer
 Dim c As String, q As String, buf As String
 Dim items(1000, 1) As Variant

 ln = Len(sour)
 q = ""
 buf = ""
 num = 0
 For i = 1 To ln
 c = Mid(sour, i, 1)
  '列区切り文字
 If (c = vbTab Or c = ",") Then
 If (q = "*") Then
 q = ""
 ElseIf (q = "") Then
 items(num, 0) = buf
 items(num, 1) = q
 num = num + 1
 buf = ""
 Else
 buf = buf & c
 End If
  'ｼﾝｸﾞﾙｸｫｰﾃｰｼｮﾝ
 ElseIf (c = "'") Then
 If (q = "") Then
 q = "'"
 buf = ""  'ｸｫｰﾃｰｼｮﾝの前の文字は無視
 ElseIf (q = "'") Then
 If (i < ln) Then
 items(num, 0) = buf
 items(num, 1) = q
 num = num + 1
 q = "*"
 buf = ""
 End If
 Else
 buf = buf & c
 End If
  'ﾀﾞﾌﾞﾙｸｵｰﾃｰｼｮﾝ
 ElseIf (c = """") Then
 If (q = "") Then
 q = """"
 buf = ""  'ｸｫｰﾃｰｼｮﾝの前の文字は無視
 ElseIf (q = """") Then
 If (i < ln) Then
 items(num, 0) = buf
 items(num, 1) = q
 num = num + 1
 q = "*"
 buf = ""
 End If
 Else
 buf = buf & c
 End If
 Else
 buf = buf & c
 End If
 Next i
 items(num, 0) = buf
 items(num, 1) = q
 num = num + 1
  '出力配列の作成
 Dim items2() As Variant
 ReDim items2(num, 1)
 For i = 0 To num
 items2(i, 0) = items(i, 0)
 items2(i, 1) = items(i, 1)
 Next i
 splitRow2Col = items2
End Function

'1列処理
Function convCol(sour As String) As String
 Dim dest As String
 Dim re As Object
 Dim pat As String
 dest = sour
 
  '指定文字削除
 Set re = CreateObject("VBScript.RegExp")
 pat = "[ ]+"
 With re
 .Pattern = pat
 .IgnoreCase = True
 .Global = True
 End With
 dest = re.Replace(dest, "")
 Set re = Nothing
 
 convCol = dest
End Function


'1行処理
Function convRow(buf As String, ln As Long, path As String, fname As String) As String
 Dim items() As Variant
 Dim sour As String
 Dim i As Integer

 items = splitRow2Col(buf)  '列に分解
 sour = items(18, 0)
 items(18, 0) = convCol(sour)  'S列変換
  '1行組み立て
 convRow = items(0, 1) & items(0, 0) & items(0, 1)
 For i = 1 To 18
 convRow = convRow & vbTab & items(i, 1) & items(i, 0) & items(i, 1)
 Next i
End Function

'1ﾌｧｲﾙ処理
Sub convFile(path As String, fname As String)
 Dim ln As Long
 Dim buf As String
 Dim fname1 As String, fname2 As String
 fname1 = path & fname
 fname2 = path & fname & ".$$$"
 Open fname1 For Input As #1
 Open fname2 For Output As #2
 ln = 1
 Do Until EOF(1)
 Line Input #1, buf
 buf = convRow(buf, ln, path, fname)
 If (buf <> "") Then Print #2, buf
 ln = ln + 1
 Loop
 Close #1
 Close #2
 Kill fname1  'ｵﾘｼﾞﾅﾙ･ﾌｧｲﾙ削除
 Name fname2 As fname1
End Sub

'ﾌｧｲﾙ探索＋処理実行
Sub delSpace(path As String, ext As String)
 Dim fcol As Object, re As Object
 Dim flist As Variant, remat As Variant
 Dim pat As String
  'ｻﾌﾞﾃﾞｨﾚｸﾄﾘ探索
 Set fcol = CreateObject("Scripting.FileSystemObject").GetFolder(path).SubFolders
 For Each flist In fcol
 Call delSpace(path & flist.Name & "/", ext)
 Next flist
 Set fcol = Nothing
  '処理対象ﾌｧｲﾙ探索＋処理実行
 Set fcol = CreateObject("Scripting.FileSystemObject").GetFolder(path).Files
 Set re = CreateObject("VBScript.RegExp")
 pat = "\." & ext & "$"
 With re
 .Pattern = pat
 .IgnoreCase = True
 .Global = True
 For Each flist In fcol
 Set remat = .Execute(flist.Name)
 If remat.Count > 0 Then Call convFile(path, flist.Name)
 Next flist
 End With
 Set re = Nothing
 Set fcol = Nothing
End Sub

Sub main()
 Call delSpace("C:/test/", "txt")
End Sub