You probably already know how to kill a werewolf, even if you don't realize it. Unlike vampires, werewolves don't have specific methods that need to be used to kill them. That doesn't mean it's an easy task, though.
Werewolves can be killed through a various number of methods, much like humans. Getting hit by a car, falling from a high elevation, or bleeding to death will all work just as well on a werewolf as they would on a human being. The challenge is not really figuring out how to kill a werewolf, it's figuring out if you're going to be able to kill that werewolf before it kills you.
I have a few recommendations to make the job easier.
The myth that werewolves will die from a silver bullet to the heart is no myth at all. It's entirely true. If you're a good shot and have bullets made of pure silver on hand, then you should have the easiest time of anyone killing a werewolf.
The introduction of silver to the heart will stop it from beating immediately. The bullet doesn't even have to do actual damage. Actually, it doesn't even really have to be a bullet. The reason the "silver bullet" became legendary is because it is by far the easiest method of getting pure silver to reach a werewolf's heart.
Other methods of getting silver to a werewolf's heart work just as well, they are just harder to pull off. Unless a werewolf voluntarily allows you to perform open heart surgery on it with a silver scalpel, you're probably going to have a hard time getting this method to work.
A variation on the bullet-to-the-heart method would be finding a way to to introduce small pieces of silver shrapnel into the blood stream. This only works if they are able to move through the blood stream and reach the heart. Once at the heart, the smallest bit of silver will cause the heart to immediately stop beating. If the silver lodges itself in the heart, you're job is done.
Let's say you
find yourself in a situation where you want to kill a werewolf, but you
don't have any silver bullets on you. Don't be embarrassed - it's
happened to us all. In this instance, a regular gun with regular
bullets may be able to do the trick.
It's not going to be as easy as using a silver bullet. Even a direct shot to the chest may not be enough to stop a werewolf, but it is better than nothing.
If you're going to try to use a gun against a werewolf, keep a few things in mind.
First, distance is your friend. Don't think that just because you were able to get your hands on a high-powered shotgun or even assult rifle that this game is in the bag. Overconfidence is the #1 killer when it comes to battling monsters. If you are standing and facing a rushing werewolf, unload all the ammo you can into it. Don't stop until you've sprayed it with enough bullets to kill it at least twice. That might not even be enough.
Werewolves are notorious for being able to take a ridiculous amount of abuse. Their muscles are much stronger than ours and their blood clots faster with a wound. They are built to last. You are not.
Snipers should have a particularly good chance against werewolves. If you can get the drop on one, aim for the head. If you can sever the connection between the spinal cord and the brain, you're going to have an easy time. If not, just make sure that you're in a position that the werewolf cannot reach. Do NOT climb a tree and snipe from there. Werewolves are excellent tree climbers.
This is a tricky one. Sharp objects such as knives, machetes, and even swords are effective against werewolves, but most of the time operating them requires close combat, which leaves a human at a significant disadvantage against a werewolf.
I can see a skilled swordsman who is quick and precise with a sharp, strong blade having success against a werewolf, but for the average person, this is just a good way to get killed.
If you are somehow able to tie or chain up a werewolf, this is probably a better method of killing than using a gun. While a werewolf could stand a barrage of bullets, it won't last long without its limbs. Or its head. Although, if you can chain up a werewolf, you probably don't need my advice seeing as you are either a genius or superhuman.
Sharp objects at a distance can be effective. An Olympic javelineer, for example, may be able to strike an unaware wolf at the other end of a field, but I wouldn't suggest trying. Maybe a bow and arrow, or a spear thrown off a building would work, but you still would likely just anger it, not kill it.
If you think I am talking about using a baseball bat to fight a
werewolf, you are probably already dead. At best, you might break a rib
or two before having your head torn clean off of your body. This goes
for 2x4's, nun-chucks, and even the mighty bo staff.
The real way to kill a werewolf with a blunt object can best be understood with simple physics. Force = Mass x Acceleration. This means, the heavier an object is multiplied by the faster the object is moving equals the greater likelihood of a dead wolf-person.
It may be a cliche, but if you can drop a suspended piano from a building, you are probably generating just the right amount of force to kill a werewolf. Ditto rolling a boulder off of a cliff. Chances are you're not going to be in such a lucky position, nor is the werewolf going to stand by while this happens, so alternative ways of combining mass and acceleration are probably necessary.
Enter the truck. It needn't be a monster truck (though the irony of the pun involved would make for a good story later), but it should be sturdy. A hefty American truck driven by a Texan would be the preferred method. Hit the gas and aim for the wolfman, and you've likely got yourself a kill.
Keep in mind, though, that werewolves are fast creatures, and quite heavy themselves. Hitting one could seriously damage your vehicle, and missing one could mean that it ends up hitching a free ride in the back. The upside, though, is that you not only have a big metal "suit of armor" surrounding you, but being inside a vehicle also makes escape much, much easier.
We could cover other methods, such as drowning or fire, but you probably
already get the idea. Killing werewolves is a tough business best left
to a professional, but knowing how to kill a werewolf could save your
life in a pinch.
My advice? Run. Fast.