参照用

'''

Sub RemoveSpacesFromFirstRowAndSpecificColumn()
Dim ws As Worksheet
Dim cell As Range
Dim targetColumn As Integer

For Each ws In ThisWorkbook.Worksheets
    ' 1行目の全てのセルに対してスペース削除
    For Each cell In ws.Range(ws.Cells(1, 1), ws.Cells(1, ws.Cells(1, ws.Columns.Count).End(xlToLeft).Column))
        cell.Value = Replace(cell.Value, " ", "")
        cell.Value = Replace(cell.Value, Chr(12288), "")
    Next cell

    ' "取引先名"列を見つける
    For i = 1 To ws.Cells(1, ws.Columns.Count).End(xlToLeft).Column
        If ws.Cells(1, i).Value = "取引先名" Then
            targetColumn = i
            Exit For
        End If
    Next i

    ' "取引先名"列の各セルに対してスペース削除
    If targetColumn > 0 Then
        For Each cell In ws.Range(ws.Cells(2, targetColumn), ws.Cells(ws.Rows.Count, targetColumn).End(xlUp))
            cell.Value = Replace(cell.Value, " ", "")
            cell.Value = Replace(cell.Value, Chr(12288), "")
        Next cell
    End If
Next ws

End Sub

'''