I just don't want a voicemail at all!

To disable voicemail on a ZTE phone, you will need to contact your service provider or follow these steps:

1. Go to the phone app
2. Tap on the three dots in the top right corner and select "Settings"
3. Select "Voicemail"
4. Disable the "Voicemail" toggle switch or follow the steps provided to disable voicemail for your specific service provider. Note that disabling voicemail may cause calls to go directly to a busy signal or be forwarded to another number, depending on your service provider's policies.
   

This is what I found, I hope you can get that fixed soon