Merging similar tags, categories, and other taxonomies is possible. You may either merge or convert one taxonomy into another from the admin panel of your website.

To do so, simply visit Plugins -> Add New page to find and install a plugin called ‘TaxoPress‘. It offers you options for adding, removing, merging, bulk editing, and deleting unused tags, categories, and custom taxonomies on any WordPress site.

Once activated the plugin enables you to merge and manage all taxonomy terms on your website from your Dashboard -> TaxoPress -> Manage Terms page as shown in the given screenshot.

The key features of the plugin include:

• Organize: In TaxoPress, you can manage taxonomies, and also terms. There are tools for you to add, rename, remove, delete, and even merge terms. You can add any term or taxonomy to any post type.
• Optimize: TaxoPress can improve your SEO with automatic term management. TaxoPress can automatically suggest relevant terms for your content and link those terms to the correct archive pages.
• Showcase: TaxoPress allows you to use your terms for advanced features such as Related Posts and Tag Clouds.

The plugin is fully functional with Managed WordPress, WordPress Ecommerce, as well as popular WordPress plugin features such as WooCommerce Product Categories, and bbPress.