Disabling and deleting the AMP plugin is not enough, since amp versions of your site’s pages are still reachable.
Besides removing the AMP plugin, you have to add the following code to your .htaccess file:
RewriteEngine On
RewriteCond %{THE_REQUEST} /\?amp=1
RewriteCond %{REQUEST_URI} (.+)/amp(.*)$
RewriteRule ^(.+)$ /$1? [L,R=301]
What it does is to redirect https://example.com/post/?amp=1 to https://example.com/post/ and also https://example.com/amp/category/ to https://example.com/category/
Why should anyone remove AMP plugin from his WordPress site?
AMP is restricting ads showing to some point, so some sites may experience revenue drop. Personally we had the plugin working for 10 days. We had to wait 72 hours until the ads start showing, and after that we had around 50% revenue drop, despite the same amount of visits to the site.