Why do we want to disable the Gutenberg editor? Because it is difficult to change habits.
You don’t need to install the plugin to use the classic editor. Because it slows down your site speed to set up more plugins. So we’ll use a smart shortcut.
How to disable Gutenberg via code?
- Go to wp-content/themes/your-theme/
- Open functions.php with note++ or etc editor
- add this code
add_filter('use_block_editor_for_post', '__return_false');
Footnote: WordPress announced that it would allow up to 2021 to use the classic editor.