Your reply to Cody has got me a little anxious, although it is an easy procedure to peel off and/ or file the cere back into the correct shape, it isn't a case of "Okay, I'll look this up and see what i can do," you are far better seeing an avian vet and asking him/ her to show you how it's done, the vet should also ask you various questions about your hen, because cere hypertrophy is often a warning sign of underlying conditions.
Cody mentioned that your hens nails need trimming, but can I also suggest you get some decent perches in the cage, wooden dowels like the one your bird is sat on are no good for the birds feet, or nails, they can also cause bumblefoot, there's so many excellent perches available which would keep your birds nails trimmed and your hen would also use the new perches to clean and shape the beak, plus of course you'd be minimising the risk of bumblefoot.