How do I dequeue js/css at the last possible moment?

I used this to determine which actions were firing, and their order:

add_action( 'shutdown', function(){
    foreach( $GLOBALS['wp_actions'] as $action => $count )
        printf( '%s (%d) <br/>' . PHP_EOL, $action, $count );

});

And that showed me that the ninja forms plugin uses a custom action nf_display_enqueue_scripts, which is what I used.