Here is something I've used before. This applies filters, filters for NA in both column C and D, then removes those rows (excluding the header). Note that this will only remove the row if NA is in BOTH columns. If NA is in C but not in D then it will not remove the row.
'Applies filter to the columns. You will want to adjust your range.
Cells.Select
Selection.AutoFilter
ActiveSheet.Range("$A$1:$D$6").AutoFilter Field:=3, Criteria1:="NA"
ActiveSheet.Range("$A$1:$D$6").AutoFilter Field:=4, Criteria1:="NA"
'Removes the rows that are displayed, except the header
Application.DisplayAlerts = False
ActiveSheet.UsedRange.Offset(1, 0).Resize(ActiveSheet.UsedRange.Rows.Count - 1).Rows.Delete
Application.DisplayAlerts = True
'Removes the filter
Cells.Select
Selection.AutoFilter
Hope that helps.