Rob Saurini

If you have more than one category associated with a post, how do you tell which category takes precedence? This plugin gives you the ability to promote the category to the main one on the post edit page.
This gets stored in post meta for later use. Soon, I will add some simple functions that will allow you to get the main category on the front end.
Use
<ul>
<li>You can use the shortcode [rs_print_main] inside the post to print out the category title.</li>
<li>In the theme, you can use rs_get_main_category_id( $post_id ) to return (not print) the id of the main category.</li>
</ul>

RS Simple Category Selector

Gives you the ability to promote categories associated with a post.

Themeisle

Valerio Souza

This plugin will completely remove the ‘/category/’ from your permalinks ( e.g. <code>mydomain.com/category/my-category/</code> to <code>mydomain.com/my-category/</code> ).
No configuration is required
<h4>Features</h4>
<ol>
<li>Better and logical permalinks like <code>mydomain.com/my-category/</code> and <code>mydomain.com/my-category/my-post/</code>.</li>
<li>Simple plugin – No configuration is required.</li>
<li>No need to modify wordpress files.</li>
<li>Doesn’t require other plugins to work.</li>
<li>Compatible with sitemap plugins.</li>
<li>Compatible with WPML.</li>
<li>Works with multiple sub-categories.</li>
<li>Works with WordPress Multisite.</li>
<li>Redirects old category permalinks to the new ones (301 redirect, good for SEO).</li>
</ol>
<h4>Heads up:</h4>
Read the <a href="https://wordpress.org/plugins/remove-category-url/faq/" rel="ugc">FAQ</a> before use.
Want to help? Use the <a href="https://wordpress.org/support/plugin/remove-category-url" rel="ugc">support</a>

Remove Category URL

This plugin removes '/category' from your category permalinks. (e.g. /category/my-category/ to /my-category/)

RS Simple Category Selector vs Remove Category URL