public function deleteUserBySlug($slug)
    {
        $userToDelete = $this->getUserBySlug($slug);
        if (empty($userToDelete)) {
            throw new \Exception('Trying to delete a user that doesn\'t exist.');
        }
        $users = $this->getUsers();
        foreach ($users as $key => $user) {
            if ($user->slug == $userToDelete->slug) {
                unset($users[$key]);
                $this->repository->users = array_values($users);
            }
        }
        $this->save();
    }