Question:

So Chanukah is over and I am putting the menorah away (sigh). What should I do with the stubs of my candles, which were often blown out before fully burning down?

Answer:

Good question. What are you to do with the leftover oil or candle stubs? The issue at hand is that fuel set aside for the mitzvah of Chanukah lights is now considered sacred and should not be used for anything else.

But what did you actually "set aside"? Technically speaking, you fulfill the mitzvah of lighting the menorah once your lights have been burning for a half-hour after nightfall. Thus, the Code of Jewish Law1 tells us that whatever is left over from the oil that was to burn in that half hour—though the flame was somehow extinguished—is consecrated for the mitzvah and should be burnt after Chanukah to ensure that it is not used for mundane purposes. If, however, you filled your cups with so much oil or used such big candles that they burnt for longer than the required time and you still had leftover fuel, you are free to do whatever you want with those leftovers as they were never "set aside" for the mitzvah lighting.

Other authorities,2 however, maintain that any leftover fuel that was placed in your menorah should be treated as "set aside," and burnt. For this reason, it is customary to burn all the leftover wicks, oil or wax from your menorah after the holiday is finished.3

Obviously, this would not apply to the oil still in the bottle and the candles still in the box, which may be used in whichever manner you see fit.