Need help closing a portal to a strange Hell-dimension?

I and one of my friends were driving around yesterday, just killing time, when we found a rock laying by the side of the road. Well, turns out that it was exotic matter, and anyway, we got bored and used it to create a traversable wormhole. I don't feel like explaining how that happened, but it involved a crap ton of math. Someone even drew a sigma. It was terrifying.

Anyway, I don't know how to put this, but I'll put it this way. We opened a portal to something that looks an awful lot like Hell. I mean, it's not literally Hell, but it sure does have a lot of lava, darkness, and things that look like common house cats but can turn you into shrews.

So, uh, here's the question. How do I shut the portal? It's kind of bad. Like, really bad. I mean, my friend can't really help because he's...uh, never mind. He's okay. He has not become a shrew. Not at all. Not at aoisdufaoiseruawh

Sorry, a shrew just ran across the keyboard. Anyway, how do I make this stop?