Plugin: Sensei – Remove action via another plugin

I am trying to remove an action within an existing WooThemes Sensei Class:

global $woothemes_sensei;
remove_action( 'sensei_single_course_modules_before', array( $woothemes_sensei->modules, 'course_modules_title' ),20 );
remove_action( 'sensei_single_course_modules_content', array( $woothemes_sensei->modules, 'course_module_content' ),30 );

I am not sure what I am doing wrong? I think I am calling the correct class with the global variable. And the labels are correct? I’ve tried various priorities.

Thank you!