Disable Gutenberg

// disable gutenberg for posts
//========================
add_filter('use_block_editor_for_post', '__return_false', 10);
// disable gutenberg for post types
//===========================
add_filter('use_block_editor_for_post_type', '__return_false', 10);
//*****--- Remove Gutenberg Block Library CSS from loading on the frontend ---*****
//===================================================================
function smartwp_remove_wp_block_library_css(){
wp_dequeue_style( 'wp-block-library' );
wp_dequeue_style( 'wp-block-library-theme' );
}
add_action( 'wp_enqueue_scripts', 'smartwp_remove_wp_block_library_css' );