Hi pks333,
I will give you my two cents, and I hope this will help you.
This new website I manage has many subdomains associated with it, and unfortunately all of them are indexed by Google. This includes dev, staging, test, and much more. I began verifying each individual subdomain as a property on Google Webmaster Tools.
Within Search Console > Google Index > Remove URL's I began removing URL's one by one (which I recorded manually based on searching Google for: site:dev.domain.com) by selecting "temporarily hide page from search results and remove from cache". Once I submitted the request I waited a full day, and so far I have removed 113 URLs from the Google Index.
For the site, in the of every page in the subdomain I placed the following tag:
I have been successful thus far. I hope this info helps.
- Ramon