I have a wordpress site that has had a large number of blog posts removed. How can i ask google to remove all these 404 page not founds, but leave the active blog posts. I see the removal tool in google webmasters but it doesnt say if it will just remove the 404s. I understand 404s naturally are removed from the index, but i want to expedite this.
You don't really have any options other then using the removal tool or waiting for them to naturally fall out of the index. If you're concerned about users following those links in Google's search results and seeing 404 errors, redirect them to a related page or another page that explains the post no longer exists and invite them to explore other pages. That way you can still take advantage of the traffic Google has to offer you.
If you are a WordPress user, you can use "HTTP 410 Gone" instead of "HTTP 404 Not Found" with your deleted pages. When Google bots recrawl your website again and found HTTP 410 Gone, Google will remove it from the index in short time. I think there are some WordPress plugins to set such custom redirect codes, such as Yoast Plugin.
This article may help you: https://yoast.com/deleting-pages-from-your-site/