In the current version of Google Play store Console as of(August 2018) here is the procedure of unpublishing your app.
When you unpublish an app, existing users can still use your app and receive app updates. Your app won’t be available for new users to find and download on Google Play.
To unpublish your app:
- Go to your Play Console.
- Select an app.
- Select Store presence > Pricing & distribution.
- In the “App Availability” section, select Unpublish.