Well, if you create a page and name it “Acne”, then the slug will automatically be /acne/.

If you want to rename a page’s slug, then go into that page and where it says Permalink, under the title field, click the Edit button. Rename it and press OK.

Usually, when you change slugs, you should perform a redirect from the old URL to the new one, but you said that the site isn’t live yet, so there’s no need for that now.

Thanks again.