We'll create fresh WordPress site with Remove CPT base installed. You have 20 minutes to test the plugin after that site we'll be deleted.
Remove custom post type base slug from url
If you’re using Yoast SEO plugin, after you change something in the Remove CPT base plugin, you should deactivate Yoast SEO and activate it back again to refresh its yoast_indexable database table, so it will generate correct og:url, canonical url and JSON-LD urls.