Is very simple to do that.
Just you need to install official Classic Editor plugin from here.
The development team comes with this intro:
Description
Classic Editor is an official plugin maintained by the WordPress team that restores the previous (“classic”) WordPress editor and the “Edit Post” screen. It makes it possible to use plugins that extend that screen, add old-style meta boxes, or otherwise depend on the previous editor.
By default, this plugin hides all functionality available in the new Block Editor (“Gutenberg”).