I would say up cause if you lean your head don't it'll make it worse.
Hold your head forward or down, pinch your nose tightly to help stop the bleeding, ice will also help ...but hold your head forward or down so you don't swallow blood which can make you sick....as in vomiting, then you'll have a whole other mess!
Hold it down to avoid aspiration.
Get some cotton , your T-shirt or any soft clean cloth and hold it softly and rush to a hospital immediately. Using ice cubes can also help a lot to easen the pain if any.
Down because otherwise the blood goes down your throat, and you can only IMAGINE how 1. Gross that would be 2. You could get sick because of the blood going into your stomach.