Cacher is the code snippet organizer for pro developers

// remove post type from theme (search for "register_post_type" in parent theme)
function custom_remove_post_type() {
    remove_action('init', 'full_name_of_parent_function');
}
add_action( 'after_setup_theme', 'custom_remove_post_type' );



// remove filter from theme
function childtheme_remove_filters(){
	remove_filter( 'excerpt_length', 'new_excerpt_length');
}
add_action( 'after_setup_theme', 'childtheme_remove_filters' );