Mario Peshev

Delete the posts from Custom Post Types that are no longer active for the install.
Navigate to Settings -> Remove Oldies and delete the posts from a given post type that is not active anymore.

DX Remove Oldies

Delete the posts from Custom Post Types that are no longer active for the install.

Sanam Maharjan

This is a plugin for converting lots of posts or pages to a custom post type (or vice versa). In the ‘convert from…’ select option you will get the lists of all the post types stores in your current database and in the ‘convert to…’ option you will get the list of all the current registered post types. In addition to this you can also convert from one taxonomy to another and the lists are populated just as that of post types.

Post Type Convertr

A bulk conversion utility for post types and taxonomies.

DX Remove Oldies vs Post Type Convertr