How to turn off TinyMCE in Wordpress

tinymce_wordpress.txt

In wordpress/wp-includes/class-wp-editor.php, look for the tinymce setting:

public static function parse_settings($editor_id, $settings) {
  $set = wp_parse_args( $settings,  array(
     ...
    'tinymce' => true, // load TinyMCE, can be used to pass settings directly to TinyMCE using an array()
     ...
  ) );

Set it to false and you should be good to go.