Mario Peshev

Delete all Custom Field entries assigned to posts that do not exist in the posts table.
Navigate to Settings -> Remove Unused CFs and delete all postmeta for non-existing posts.

DX Remove Unused Custom Fields

Does exactly what it says.
Installed, navigate to the settings page, click "Delete" and Done! Cannot be easier than that.
Thank you!



Simply Awesome!

Delete the Custom Fields from your postmeta table where assigned posts no longer exist.

prettyboymp

CMS Press opens up the ability to create and manage custom content types and taxonomies for your WordPress site. 
It adds the flexibility to have more than just posts and pages for content by allowing the user to register their 
own post_types that can use their separate theming from the post and page template along with its own permalink structure.
Along with custom post_types, CMS Press gives users the ability to register their own taxonomies. With the addition of 
custom taxonomies, a user can tag or categorize content separate from the default tags and categories.

CMS Press

Adds ability to create custom content types (post_types) and taxonomies to your WordPress installation.

DX Remove Unused Custom Fields vs CMS Press