WordPress Remove Old Slugs is simple old permalink remover from WordPress database. After you change your blog’s permalink structure, WordPress create new permalinks but still all your old permalinks stay there in your site’s MySQL database and occupies unnecessary space in your server. Using this new plugin you can remove all old permalinks in just a single click.
Install and activate WordPress Remove Old Slugs. After activation visit Dashboard -> Tools -> Remove Old Slugs and click Start button to proceed.