A very peculiar issue in need of drastic steps perhaps?

My blog resides on an addon domain from another site. If anyone isn’t familiar with the concept, here’s a brief explanation: site.com allows me to set up addon domains that operate just like a domain but are actually subdomains. So my blog, blog.com, is actually blog.site.com – but no one can tell – except obviously Google.

Suddenly several of my posts have been revealed to reside on a subdomain. People – if they google the right keyword – can find several posts on the domain blog.site.com.

I need to prevent this.

I set up a no index.nofollow meta tag in the header of my blog. I also put a robot.txt file in the folder my blog resides in on the server. Although this will destroy my presence in Google, it will solve the issue in the longterm.

Another solution is to delete the pages that Google has indexed in the blog.site.com format. But how do you actually delete “pages” so the result is a “page not found” error. Just deleting the posts won’t achieve this.

Any advice on any or all of this odd issue?