Disable Gutenberg without plugin

Identify Your WordPress Version

On your WordPress Dashboard, scroll down to the bottom and on right end, you will see WordPress Version number. You can also find in “At a Glance” WordPress admin widget in Dashboard.

For WordPress Version 5.0 and above

1. Edit functions.php
2. Add following code to disable Gutenberg for all posts

add_filter(‘use_block_editor_for_post’, ‘__return_false’, 10);

For WordPress Version below 5.0

1. Edit functions .php
2. Add following code to disable Gutenberg for all posts

add_filter(‘gutenberg_can_edit_post’, ‘__return_false’, 10);