To disable Gutenberg editor also known as block editor without using a WordPress plugin. You will need access to your install files using FTP or file manager.
Login to your website install directory, inside your theme’s files, find a file named functions.php file. Download the file, and make a copy of it as a backup just in case something happens you will be able to revert back the changes.
Open the functions.php file using a file editor like vscode or sublime text and add the below line of code. Save and upload the file back to your site.
// Disable Gutenberg on the back end. add_filter( 'use_block_editor_for_post', '__return_false' ); // Disables the block editor from managing widgets. add_filter( 'use_widgets_block_editor', '__return_false' );
That’s it you will now be reverted back to the classic editor as before. In case you would like to revert back to block or Gutenberg editor simply comment on the above line of code.
Alternatives to disable Gutenberg block editor
You can also install and active one of the below plugins to disable Gutenberg or block editor in WordPress. Just in case you are not comfortable with editing your website files.