404 errors from urls that read domain/blog/tag/

I set up a WordPress site with the WordPress install in a blog directory and re-routed to the root url.

I am getting 404 errors in Google Webmaster tools that read:
URL: https://www.domainname.com/blog/tag/tagname
Under “Linked from”, it lists 8 links to posts on the blog.

I have looked through the html code of all those 8 posts and the URL it mentions is not in the posts. The tags on the posts also differ from the tag name in the URL.

However, the tag name mentioned in the URL is listed under tags and is being used by other blog posts.

The permalinks are set to post name and are correct.

Any tips on how to fix this error? Will deleting the tags fix this issue?

Thanks