Private Web App being indexing

hello folks,
i seen today on google that our web app for use of clients/demo purpose is being indexing by Google. how do i remove it? from the Google (submit a removal request) or maybe put something in meta of pages to not to list. can i do that?

i never submitted it to google at first place. how did it go there

You can most certainly go into Google Webmaster tools and do a removal request. You can also disallow in robots.txt