Using New Outlook on Windows for personal email, calendar, and contact management
What is the "ghost email"? If it is a weird address in the format of Outlook_[big long code]@ outlook.com, it is because you have a non-Microsoft address set as primary on your Microsoft account. Your address is used only to sign into Microsoft services and the weird address is a placeholder for an outlook.com address.
To get rid of it, add an outlook.com alias to your account and set it as primary at https://account.microsoft.com/profile/ and it will go away.
Microsoft has more information in this article:
Outlook.com email account appears as "outlook_[long series of letters and numbers]@outlook.com" in Outlook for Windows
https://support.microsoft.com/office/90ed7938-7f21-4cb5-a69d-a3b79ea4eafd
If it is something else, please explain what you mean by ghost address.