Removing /blog/ from permalinks settings

Hi all, I have tried to remove the /blog/ part of the permalinks setting but it refused to go away.

I am now using the Branding plugin which I have set to hide the permalinks menu from my client's menu but still want to set all my main top wordpress install to not have 'blog' automatically in every post and page URL, and additionally I want to avoid this for all my new sites using the multi site set up.

Can someone advise please?

Thanks
Guy