Custom post type Parent page/post

I can’t get get this thing to work, what i’m trying to do is create a parent page for custom post type. e.g. slug /category/subcategory every subcategory is a custom post type. What i want is one of those pages to be the parent page (under /category/ slug)
How can this be done? I tried, hierarchical parent /category/category/ and wanted to remove the custom post slug, but no luck. Keep getting the archive page with all custom post pages/posts.

thnks