To edit post slug, click on the edit button below the post title

The link after editing

I will advise you only edit an old published post with low performance

What to do

301 redirection is what you need after changing your post link, and it’s the best way to redirect your users and search engine to the corrected page link, this gives the best user experience to your visitor. What 301 status means is that your page has been moved permanently to another address.

301 redirection with Wordpress

One of the advantages of using WordPress is that it gives you access to lots of plugins. Redirection plugin is a free plugin with 301 redirection features, and we will be making use of it as an example for the Wordpress users. In case you have Yoast SEO premium, then the redirection feature is already available for you. You can also try any other plugin, just make sure it has the 301 redirection feature.