SQL query for renaming the posts:

UPDATE  `wp_posts` SET  `post_type` =  '<new post type name>' WHERE  `post_type` = '<old post type name>';
SQL query for renaming taxonomy:

UPDATE  `wp_term_taxonomy` SET  `taxonomy` =  '<new taxonomy name>' WHERE  `taxonomy` = '<old taxonomy name>';

http://wordpress.stackexchange.com/questions/1037/renaming-custom-post-types-and-taxonomies

Use below SQL code and replace references within the theme files.

WP - Rename custom post types and taxonomies

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