Might you need one of these Admin capabilities?
- delete_others_pages
- delete_others_posts
- delete_pages
- delete_plugins
- delete_posts
- delete_private_pages
- delete_private_posts
- delete_published_pages
- delete_published_posts
Unless you’ve modified the default capabilities for Administrator, to remove one or more of these capabilities, you should be able to delete any Post (of any Post-Type) as an Admin user.