Delete Chart Series Across Sheets But Skip Protected Sheets

I have received following macro from someone to delete series but the problem is that it gives error when some sheets are protected, and I want those sheets to protected. When run it will ignore/leave protected sheets but delete series only from unprotected sheets

Private Sub CommandButton1_Click()
Dim Rng As Range, i As Long, r As Range, lVal, uVal
Dim DeleteCount As Double
Dim lRow As Long
Dim dr As Long
Dim dc As Long
dc = Sheets("Deleted Numbers").UsedRange.Columns.Count - 1
dr = Cells(Rows.Count, Sheets("Deleted Numbers").UsedRange.Columns.Count - 1).End(xlUp).Row + 1
If dr = 60001 Then ................