I went to Network Admin -> Sites -> (root site) Edit -> Settings (tab), and entered “%postname%” in “Permalink Structure” field (after some experimenting with leaving it blank etc)
When I click on a post name I am getting the correct
https://domain-name.com/post-name
, but when I click on one of the category names, I am still getting
https://domain-name.com/blog/category-name
I went to (root site) Dashboard -> SEO (Yoast SEO plugin) -> Permalinks, and unchecked “Strip the category base (usually /category/) from the category URL” and got the following:
https://domain-name.com/category/category-name
After checking it back again it goes back to
https://domain-name.com/blog/category-name
…and I made sure to go back to the Site Settings, and saving the %postname% in “Permalink Structure” as the last thing that I was doing before going to the site etc…
So basically, I was able to get rid from /blog slug from a post name URL, but it still remains in the URL in a category name. If I dont enter postname, and leave it blank I get https://domain-name.com/?p=123, or any of the other options (instead of a post name that I want)