Hickeys are bruises under the skin they will go away on their own time. You can help speed it up as any bruise and place a cold compress on it. Depending on how quick you do this and the severity of the hickey it can help. Time will be the only real remedy though. Sorry.
I cannot help but remember hearing all these "remedies"when I was a teenager LOL You would NOT want to rub a hard brush or anything else on a bruise that would only make it worse not better would you rub a bruise to make it better anywhere else?