Adding/Editing Posts - Changing a Post’s URL
WordPress automatically forms a URL (aka the post “permalink”) for your website’s posts based on the title of the post and the date it is published.
You have limited control over how the URLs are formed. To edit a post’s URL, click the Edit button after the Permalink, just under the page title box:
You can change the portion highlighted in yellow to reflect a shorter, neater URL if desired. Spaces and fancy characters will not work.