iCDB Project Backup has features and settings that automatically remove backups.
You can preserve a backup from these operations by setting it to be Persistent.
This is only available when you have a project open, not a backup. See Invoking the iCDB Project Backup Utility.
Note: The Persistent setting does not apply to manual removal. If you have permission to remove a backup manually, you can remove the backup even if it is set to Persistent.