Just be aware that in your sub test2() below that if one cell is 6, and the
other -6 it will still say both are zero.
Also, if by 'delete' the original poster meant just to clear the contents,
with a line such as:
cell.EntireRow.ClearContents
to replace the msgbox line, then the macro will work as required.
If instead, the OP wanted to remove the row and close up the gap with
cell.EntireRow.Delete
then if there are two rows next to each other which need deleting, it will
miss the second one, because it runs from the top downwards.
So to be constructive, try it with these small adjustments
Sub test2()
Dim ws As Worksheet
Set ws = Worksheets("sheet1")
Dim lastrow As Long
Dim cell As Range
Dim i As Integer
lastrow = ws.Cells(Rows.Count, "B").End(xlUp).Row
With ws.Range("B1:B" & lastrow)
For i = .Cells.Count To 1 Step -1
If .Cells(i) = 0 And .Cells(i).Offset(0, 1) = 0 Then
MsgBox "row " & .Cells(i).Row & ", cells B and C are both 0"
.Cells(i).EntireRow.Delete
End If
Next i
End With
End Sub