Cache clearing without drush I am using Drupal 8, and I am wondering how I can clear more caches than the button in admin/config/development/performance does.

I have had trouble with installing Drush, so I am looking for any alternative solutions.
Just execute core/rebuild.php.
As the documentation says, it rebuilds the cache even when Drupal doesn't work; it require a token you can generate with scripts/rebuild_token_calculator.sh, so you call it as http://example.com/core/rebuild.php?token=TOKEN_YOU_GET_FROM_THE_SCRIPT.