Deleting backups for Vultr instances completely removes the files from your account. You should perform this operation after restoring the required backup files. You can also consider converting a backup to a snapshot before deleting the backup. After deleting a backup, you can't undo the operation and you should take great care before making the decision.
Follow this guide to delete Backups for Vultr instances using the Vultr Customer Portal.
Navigate to Products, select Orchestration, then click Backups. Click the delete icon to remove the backup.
Click Remove Backup to confirm.