Gutenberg is the name of the project to create a new editor experience for WordPress. The goal is to create a new post and page editing experience that makes it easy for anyone to create rich post layouts. It's planned to be merged into WordPress core in the version 5.0. Gutenberg will changes the way you create content a lot. You'll be able to add complex elements to the post content via blocks. They can be images with overlay text or a list of items with thumbnails.
While Gutenberg is a wonderful editor for bloggers, publishing websites (news, media), even a restaurant with custom menu built with Gutenberg, it probably is not a good choice with other WordPress websites. WordPress is now much more than a publishing platform. It can be a real-estate website where a lot of data for properties. It can also be a job board or a forum. In these kinds of websites, using an editor like Gutenberg might be confused and sometimes hard to use. So, how to disable Gutenberg? And how to revert back to the WordPress classic editor?
How to disable Gutenberg editor?
At the moment, you don't need to do anything. Because Gutenberg hasn't been merged into the WordPress core yet. But if you already installed the Gutenberg plugin to try and use it, then you'll see it replaces the WordPress classic editor by default. Then you'll need a way to disable it.
To disable Gutenberg and revert back to the classic editor, just use the plugin Classic Editor:
This plugin will add a new submenu Add New (Classic) under Posts menu where you can add new posts with the classic editor. Besides, it also adds a Edit (Classic) link when you hover the post in the post list able.
Now you can edit posts in the classic editor or Gutenberg as you wish.
If you don't see those links, navigate to Settings → Writing and you'll see the options as follows:
Make sure you tick the checkbox "Do not replace the editor. Add alternate links to the Posts and Pages screens for editing with the Classic editor.". Save the settings and you will see those alternate links.
If you don't want to use Classic Editor plugin, try these ways.
Disabling Gutenberg is not only useful for non-blog websites, but also useful for websites that heavily use meta boxes. We have written about this problem in a previous post. At the moment, after 4 months, the Gutenberg team has made a great progress. According to that, normal meta boxes will continue to work with Gutenberg. Of course, there will be needs for improving Gutenberg to make it works seamlessly. In the mean time, turn Gutenberg off is a good choice if you're not going to use it.
- Gutenberg and the Future of Meta Box
- How to Disable Gutenberg and Use the WordPress Classic Editor
- Meta Box is Now Compatible with Gutenberg
- An Update on WordPress 5.0, Gutenberg and Meta Box
- How To Disable Gutenberg Without Using Plugins
- Introducing MB Blocks - Creating Gutenberg Blocks Now Made Easy
- Build Gutenberg Blocks Visually With Meta Box Builder
- Top 7 Plugins to Add Extra Blocks for Gutenberg [2021]
- Full Site Editing (FSE) - All You Need To Know - P1 - Overview
- Gutenberg vs. Page Builders - What is Better & Faster? In-depth Comparison
- Review Quadrat - A WordPress Block Theme
- Full Site Editing - P5: What Are Block Patterns in Gutenberg? How to Create Them?
Gutenberg vs. Page Builders - What is Better & Faster? In-depth Comparison 
An Update on WordPress 5.0, Gutenberg and Meta Box 
Gutenberg and the Future of Meta Box
Another method if you don't want settings or options:
https://wordpress.org/plugins/disable-gutenberg-littlebizzy/
Here's one that gives you every possible option, plus gives a button to switch between editors as well: https://wordpress.org/plugins/guten-free-options/
Good post, Gutenberg is a really headache for us. Thx for the info!
I have a paid wordpress.com site. I hate the Gutenberg editor and need the Classic Editor. With the Covid pandemic, I put my site on hold until recently, and found that the Classic Editor was gone. The only way that I see to get the Classic Editor back is via a plugin - not allowed for wordpres.com, only for wordpress.org . I can use a plugin if I switch to a business plan, about $200 or $300 (not happening!). I've also seen that I can use some "code" to get Classic back, but was warned that one false step and my site would be kaput! Not too keen on trying coding, but if there s a simple "foolproof" option, I may get on board. Adding links are a pain, changing justification is a pain, my "way of life" in the blogging world is now a pain. Am I totally screwed? Is there no viable solution? Thanks.
I'd recommend switching out of WordPress.com to avoid the issues.