I know that as long as channukah candles are lit and the candle goes out by itself, you already did the mitzvah. I also know that you should have the channukah candles lit for at least 30 minutes. What I'm wondering about is what happens if you're going to be leaving the house, and you decide to blow out the candles before you leave, to prevent the unlikely (but still real) possibility of a candle falling and starting a fire in your house. Are you allowed to do so? If you do so, should you relight the candles again when you get home?