Need to stop pulling sub-site content into main site

I took over of a multisite last year, but did not originally create it. The main site is currently pulling all blog posts from 3 sub-sites. My company now wants the main blog to behave like the others, with its own posts only. Any ideas on how the main blog is pulling in the posts and how I can stop it? My site is blogs.aecom.com. Thanks, Violet