How To Remove WHM Login Page From Google Index?

Somehow our server's WHM login page has managed to be indexed.

IE server.example.com:2087 and also server.example.com:2087?locale=

We have no idea how this happened as there aren't any links to it and we've never submitted the URL to Google. It is a VPS rather than shared hosting, so in theory we should be able to control this.

How can we get this deindexed and never reindexed? Anyone have experience with this before?

Thanks!