How can I disable Yoast SEO's Twitter Cards via PHP?

I am attempting to disable Yoast SEO's Twitter Cards using the hook system. I've been able to disable Yoast's Open Graph using the following method, but for some reason, the Twitter cards refuse to go away. Here's my current code:

// Inside my Open Graph function:
global $wpseo_og; 
remove_action( 'wpseo_head', array( $wpseo_og, 'opengraph' ), 30 );

// Inside my Twitter Card function:
global $wpseo_twitter;
remove_action( 'wpseo_head', array( $wpseo_twitter, 'twitter' ), 40 );

I've seen this code on several forums, but for some reason, only the Open Graph removal seems to be working on my site. Any help would be greatly appreciated.

via Chebli Mohamed