This plugin will automatically 301 redirect your old 'postname' format permalinks so you don't lose your precious SEO.

This plugin removes the mandatory 'Category Base' from your category permalinks. It's compatible with WPML.

Custom Permalinks Manager for WooCommerce allows you to change WooCommerce permalinks and remove product and category slugs from URLs.

Removes the category base slug from the category archive permalinks (URL's).