One of the many things that you can control in the template for your Articulate Presenter player is whether or not Articulate creates a file containing a launch button to open your course in a new window. The selection comes under the "Other" menu in the Player Template part of the Articulate ribbon in PowerPoint. If you have the Launch in New Window selection checked, Articulate will create a file called launcher.html when your presentation is published, along with the player.html file. Laucher.html contains a button that opens play.html in a new window.

Often times your LMS will also have a feature that controls whether or not the player.html opens in a new window, so you may not need the launch.html file. In the following screencast I have addressed in more detail how to control whether or not launch.html is created.