WordPress now comes with the Gutenberg Editor (aka. Block Editor) activated by default. This is more useful than the Classic editor and makes it easier for the user to add content to the site. However, if you are not a fan of the Gutenberg editor, you can enable this module to disable the Gutenberg editor.
Activate Disable Gutenberg Editor Module
In the Admin Optimizer module page, click to enable the Disable Gutenberg Editor module (under the Disable Features section). Press Save Changes to save the changes.
Check if the module is working
To check if the module is working, simply open any post in the Post Editor. You should see the Classic editor in place of the block editor.