How to move Composer created folder of drupal-8.x.x up one level to html?
Since you are using composer to manage dependencies, you should install Drupal with Composer instead of using drush pm-download:

https://www.drupal.org/docs/develop/using-composer/using-composer-to-manage-drupal-site-dependencies#download-core

Also, you should use Composer to manage contributed modules instead of using drush pm-install:

https://www.drupal.org/docs/develop/using-composer/using-composer-to-manage-drupal-site-dependencies#managing-contributed

You can even use Composer to manage third-party libraries:

https://www.drupal.org/docs/develop/using-composer/using-composer-to-manage-drupal-site-dependencies#third-party-libraries

And to apply patches to Drupal core and contrib modules:

https://www.drupal.org/docs/develop/using-composer/using-composer-to-manage-drupal-site-dependencies#patches

Don't worry, you'll still use drush for a lot of things -- but once you've switched to using Composer to manage dependencies, you should stick with it as much as possible and avoid using Drush makefiles or installing / upgrading with Drush.

Here's an article with some common "gotchas" you may encounter when managing Drupal with Composer:

https://www.jeffgeerling.com/blog/2017/composer-and-drupal-are-still-strange-bedfellows