Jars used for unhex candle

I want to burn a Unhex candle for my sister's boyfriend to remove possible hexes, I want to cut a piece of his unwashed t-shirt along with his picture, but I have a xl unhex that I would like to use at a later time... So my question is, what do I do with the jar once I've burned the unhex for 6+ hours?

Thanks, anyone who can help me with this!