Let it sit. Assuming it's not just loaded with fusel alcohols. My best example of this is my first batch of mead. For the first year, it was so alcoholic. Undrinkable. During the second year, the alcohol was fading and it was becoming more drinkable. Just hit year three, and wow, it's pretty tasty now. I thought I had screwed up on fermentation, but having read a fair amount, didn't want to dump it and just sat on it for a while, hoping that would clean it up and mellow it out. Well, it took about 3 years for the mead, but it did. If a mead can do that, I'm sure a beer, with many more, stronger flavors, can do the same (and I've had that happen too, doesn't take as long for beer luckily).
So, my advice, sit on it. Hopefully it doesn't take a year or two, but you'll be surprised how big of a difference even just 6 months can make.