D365 F&O environments should ideally always be deployed using an unnamed account (e.g. ). This ensures that if users leave the business for any reason, there are no security implications, or worse still, the business is not stuck unable to maintain or update any environments.
However, for various reasons, it may not be possible to get the environment administrator right in the first instance, and it needs to be changed later on. If this has happened to you, you’re in the right place!