How to clear voicemail badge (little number notification) without setting up voicemail box

I do enterprise mobility for a company and one of the users does not want their voicemail set up. However, they have received a voicemail and I can't clear the notification/badge.

Is there a way to clear the notification/badge without the user setting up their voicemail box?

Even though they can already get voicemails they still do not want to set their voicemail box up.