code: 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();
      }
docs: 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)