delete rows based on a criteria

Or if you prefere a macro code:

Option Explicit

Sub Delete_Row()

Dim i As Integer

For i = Range("C" & Rows.Count).End(xlUp).Row To 1 Step -1

If Cells(i, 3).Value >= 40 And Cells(i, 3).Value <= 50 Then
 Rows(i).Delete
End If
Next i

End Sub

Alf