Milankumar Sanandia

This plugin will WP Disable Block Editor & enable the Classic Editor and original Edit Post screen (TinyMCE, meta boxes, etc all).
<ul>
<li> Disable Block Editor on page and Enabled Old Editor.</li>
<li>Admin Option for Enabled/Disable Gutenberg Block Editor.</li>
</ul>

WP Disable Block Editor

This plugin will WP Disable Block Editor & enable the Classic Editor and original Edit Post screen (TinyMCE, meta boxes, etc all).

Farid Mia

This plugin disables the Gutenberg Editor and Gutenberg widget block. 
You can totally disable Gutenberg. After activating this plugin, the classic editor and widget will be enabled automatically.

Disable Classic Editor and Widget

This plugin disables the Gutenberg Editor and Gutenberg widget block.

WP Disable Block Editor vs Disable Classic Editor and Widget