Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello EnajE1,
Welcome to Microsoft Community.
According to your description, your former work account is no longer valid because you already retired two years. Regarding your concern, seems you would like to remove this account sign-in window. May I carefully confirm with you, are you want to contain the startup or you would like to disable it? If so, you could refer Windows Startup Settings (including safe mode) (microsoft.com) to disable startup. If you would like to use very specific Microsoft products but just want to remove account from this sign-in software data, you can search Credential Manager in Windows default search bar, open it, then select Windows Credentials > Select the account you would like to remove then click the expand button > click Remove to remove this account, like these screenshots show:
Kind Regards,
Tommy