How can I remove a spam page from my website index?

Having same issue. Had 300+ pages indexed (as original content). Within a week, 3.5million pages were indexed and 3.7 million pages not indexed. In Total: 7.2 million pages … Not sure what to do, added “noindex” meta tag, it helped me to not get all 7.2 mill indexed, but how to remove indexed ones? Because when you using disavow tool and add link /collection/vendors it removes whole /collections/ from indexing, not only collections/vendors/ .