Sub www()
Dim i&, x&, a&
     i = Cells(Rows.Count, 1).End(xlUp).Row
     x = ((i - 1) / 100) * 10
     MsgBox "10% строк = " & x
     For a = Cells(Rows.Count, 1).End(xlUp).Row To 2 Step -1
         If x = a Then Exit Sub
         Rows(a + 1).EntireRow.Delete
     Next
End Sub

Sub www()
Dim i&, x&, a&

     i = Cells(Rows.Count, 1).End(xlUp).Row
     x = ((i - 1) / 100) * 10
     MsgBox "10% строк = " & x
         
      
     With Range("A1").CurrentRegion
          
         With .Offset(1, .Columns.Count).Resize(.Rows.Count - 1, 1)
             .Formula = "=RAND()"
             .Calculate
             .Copy
             .PasteSpecial xlPasteValues
         End With
         Application.CutCopyMode = False
          
         With .Offset(, .Columns.Count).Resize(1, 1)
             .Value = "Слчис"
             .Sort Key1:=.Cells(1, 1), Header:=xlYes
         End With
          
         .Columns(.Columns.Count + 1).Clear
     End With
      
     Rows(CStr(x + 1 & ":" & Cells(Rows.Count, 1).End(xlUp).Row)).EntireRow.Delete
      
End Sub

Sub www()
Dim a&, i&, x&
Dim c As Range
Application.ScreenUpdating = False
     i = Cells(Rows.Count, 2).End(xlUp).Row
     x = ((i - 1) / 100) * 10
     MsgBox "10% строк = " & x
         For a = Cells(Rows.Count, 1).End(xlUp).Row To 2 Step -1
             If x = a Or x = 0 Then Exit Sub
             Rows(Int(((a) * Rnd) + 2)).EntireRow.Delete
         Next
Application.ScreenUpdating = True
End Sub