How to delete Users?

I have done a lot of testing, installing my app, uninstalling it, etc. Now I would like to delete all of these Users I have created. I thought they would go away automatically as I unsubscribed and uninstalled the app but they do not. How do I force deletion of Users?

I also emailed this question to webpushr support and they replied as follows,

"They will eventually go away. We depend on a signal from browser gateways that the user is no longer active. Once we receive it, we delete the user. We also offer a feature called “optimize users” available via a link on our dashboard. This feature let’s you delete users that have not visited your site for a while. You can eventually use that (but not right now as it wouldn’t be effective, assuming you recently started using Webpushr).

Let us know if you have any other questions.

Regards,
Webpushr Support Team"