Clear template cache from the CLI?
Craft-Scripts will do this for you: https://github.com/nystudio107/craft-scripts#clear_cachessh

You can see what it does via the source: https://github.com/nystudio107/craft-scripts/blob/master/scripts/clear_caches.sh

As for cache/clear this clear's Yii2's cache... which Craft CMS uses for almost nothing. Template Caches are always in the db, compiled templates are always cached on disk as files, and so on.