The easiest way to disable Gutenberg is to install my free plugin, Disable Gutenberg. It is a simple plugin focused on one thing: disabling Gutenberg and restoring the default classic WP Editor screen. Just enable the plugin, choose your options and done. Options include:

• Disable Gutenberg completely (all post types)
• Impair Gutenberg only on specific post types
• Defuse Gutenberg for specific user roles
• Weken Gutenberg for any theme templates
• Option to hide the “Try Gutenberg callout nag
• Option to hide the Gutenberg menu item

 

It’s flexible, simple and easy to use.