Sprint S6, How to disable built in voicemail app?

[jcthorne#AC]

I use google voice so have no need of the Samsung voicemail app. Yet it keeps notifying me of voicemails from long ago. How do I turn it off?

 

[B. Diddy]

If you open the Phone app, tap Menu>Settings>Call Settings>Voicemail, are you able to erase the voicemail number?