lib/Twig/lib/Twig/Environment.php
public function removeExtension($name)
    {
        @trigger_error(sprintf('The %s method is deprecated since version 1.12 and will be removed in Twig 2.0.', __METHOD__), E_USER_DEPRECATED);

        if ($this->extensionInitialized) {
            throw new LogicException(sprintf('Unable to remove extension "%s" as extensions have already been initialized.', $name));
        }

        $class = ltrim($name, '\\');
        if (!isset($this->extensionsByClass[$class]) && class_exists($class, false)) {
            // For BC/FC with namespaced aliases
            $class = new ReflectionClass($class);
            $class = $class->name;
        }

        if (isset($this->extensions[$class])) {
            if ($class !== get_class($this->extensions[$class])) {
                @trigger_error(sprintf('Referencing the "%s" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.', $class), E_USER_DEPRECATED);
            }

            unset($this->extensions[$class]);
        }

        unset($this->extensions[$class]);
        $this->updateOptionsHash();
    }
public function removeExtension($name)
    {
        @trigger_error(sprintf('The %s method is deprecated since version 1.12 and will be removed in Twig 2.0.', __METHOD__), E_USER_DEPRECATED);

        if ($this->extensionInitialized) {
            throw new LogicException(sprintf('Unable to remove extension "%s" as extensions have already been initialized.', $name));
        }

        $class = ltrim($name, '\\');
        if (!isset($this->extensionsByClass[$class]) && class_exists($class, false)) {
            // For BC/FC with namespaced aliases
            $class = new ReflectionClass($class);
            $class = $class->name;
        }

        if (isset($this->extensions[$class])) {
            if ($class !== get_class($this->extensions[$class])) {
                @trigger_error(sprintf('Referencing the "%s" extension by its name (defined by getName()) is deprecated since 1.26 and will be removed in Twig 2.0. Use the Fully Qualified Extension Class Name instead.', $class), E_USER_DEPRECATED);
            }

            unset($this->extensions[$class]);
        }

        unset($this->extensions[$class]);
        $this->updateOptionsHash();
    }
Removes an extension by name.

This method is deprecated and you should not use it.

@param string $name The extension name

@deprecated since 1.12 (to be removed in 2.0)