How to split spreadsheet into multiple spreadsheets with set number of rows?

I updated the code by @Fer Garcia to Mac users ;), the change only in file saving method

Sub Test()


Dim wb As Workbook
  Dim ThisSheet As Worksheet
  Dim NumOfColumns As Integer
  Dim RangeToCopy As Range
  Dim RangeOfHeader As Range        'data (range) of header row
  Dim WorkbookCounter As Integer
  Dim RowsInFile                    'how many rows (incl. header) in new files?

  Application.ScreenUpdating = False

  'Initialize data
  Set ThisSheet = ThisWorkbook.ActiveSheet
  NumOfColumns = ThisSheet.UsedRange.Columns.Count
  WorkbookCounter = 1
  RowsInFile = 150                   'as your example, just 10 rows per file

  'Copy the data of the first row (header)
  Set RangeOfHeader = ThisSheet.Range(ThisSheet.Cells(1, 1), ThisSheet.Cells(1, NumOfColumns))

  For p = 2 To ThisSheet.UsedRange.Rows.Count Step RowsInFile - 1
    Set wb = Workbooks.Add

    'Paste the header row in new file
    RangeOfHeader.Copy wb.Sheets(1).Range("A1")

    'Paste the chunk of rows for this file
    Set RangeToCopy = ThisSheet.Range(ThisSheet.Cells(p, 1), ThisSheet.Cells(p + RowsInFile - 2, NumOfColumns))
    RangeToCopy.Copy wb.Sheets(1).Range("A2")

    'Save the new workbook, and close it

    wb.SaveAs "Test" & WorkbookCounter & ".xls", FileFormat:=57
    wb.Close

    'Increment file counter
    WorkbookCounter = WorkbookCounter + 1
  Next p

  Application.ScreenUpdating = True
  Set wb = Nothing
End Sub

Your macro is just splitting all the rows in the selected range, including the header row in the first row (so it will appear just one time, in the first file). I modified the macro for what you're asking; it's easy, review the comments I wrote to see what it does.

Sub Test()
  Dim wb As Workbook
  Dim ThisSheet As Worksheet
  Dim NumOfColumns As Integer
  Dim RangeToCopy As Range
  Dim RangeOfHeader As Range        'data (range) of header row
  Dim WorkbookCounter As Integer
  Dim RowsInFile                    'how many rows (incl. header) in new files?

  Application.ScreenUpdating = False

  'Initialize data
  Set ThisSheet = ThisWorkbook.ActiveSheet
  NumOfColumns = ThisSheet.UsedRange.Columns.Count
  WorkbookCounter = 1
  RowsInFile = 10                   'as your example, just 10 rows per file

  'Copy the data of the first row (header)
  Set RangeOfHeader = ThisSheet.Range(ThisSheet.Cells(1, 1), ThisSheet.Cells(1, NumOfColumns))

  For p = 2 To ThisSheet.UsedRange.Rows.Count Step RowsInFile - 1
    Set wb = Workbooks.Add

    'Paste the header row in new file
    RangeOfHeader.Copy wb.Sheets(1).Range("A1")

    'Paste the chunk of rows for this file
    Set RangeToCopy = ThisSheet.Range(ThisSheet.Cells(p, 1), ThisSheet.Cells(p + RowsInFile - 2, NumOfColumns))
    RangeToCopy.Copy wb.Sheets(1).Range("A2")

    'Save the new workbook, and close it
    wb.SaveAs ThisWorkbook.Path & "\test" & WorkbookCounter
    wb.Close

    'Increment file counter
    WorkbookCounter = WorkbookCounter + 1
  Next p

  Application.ScreenUpdating = True
  Set wb = Nothing
End Sub

Hope this helps.