As an Admin/Supervisor, you can delete voicemails within your AVOXI account anytime.  

To do so, follow the below guide:

1. To get started, log in to your Genius account 
2. Then select the "Voicemail" icon located on the top right  navigator
3. Next, click the "Voicemail" tab 
4. On the voicemail homepage, scroll down to "All Voicemails." 
5. Use the box tick to select which voicemails you would like to delete
6. Lastly, select the three dots and then "Delete Voicemail."