Walking supernatural

How do we kill that?

"The crossbow guy's back, Sammy." Dean whispered. Daryl unlocked and slid their cell open, he stepped in. "Alright, new boys. Where are you from? Do you have any buddies who might come looking for you? How big is your camp?" Daryl questioned. "Uh.. Only us, like we said we're from Ohio. There was this purple pool after we killed a demon, we jumped in and now we're here. Wherever here is." Sam gestured around them with his hands. "You probably imagined all that, boy. You've got a head wound, what from?" Daryl asked. "Fighting the previously mentioned demon!" Dean said. "Dean, this guy could help us figure out where we are and how to get back to our world." Sam whispered to him. "Fine." Dean said and leaned back in his seat.
  "This is a base. You're in the zombie apocalypse. Do you know how to kill zombies?" Daryl continued, slightly glaring at Dean. "No we don't, how do we kill a zombie?" Sam asked. "A blow to the head or destroying it's brain. Anything else will just slow them down a bit." Daryl replied.