From within your account:
- Login to your account
- Select Numbers
- Select on your number
- Select the Voicemail/Messages tab
- Select the drop-down menu for Ring my phone, then send calls to VM after
- Select Never - VM off
Selecting Never - VM off will disable the NumberBarn voicemail. Voice messages will be left on the number to which you are forwarding.
Note this does not disable SMS for your number.