There is no safe way to dispose of the werewolf, a resilient and very harmful monster. Unlike vampires, they are not generally thought to be harmed by religious artifacts such as crucifixes and holy water.
In some cases, the werewolf is portrayed as being invincible and nearly indestructible, with decapitation of its head and removal of its heart as the only surefire way to kill one.
In the old Hollywood version of the myth, a werewolf can be killed with a silver bullet, and is allergic to the herb wolf's bane. More modern films have werewolves being killed by various silver objects.
To tell the truth, since there is little opportunity when a werewolf is really vulnerable in its animal form, over the centuries werewolf hunters have learned to wait until the creature has shifted back to its human shape.