Hi John,
First thing you should do is remove that work account from your device settings, since it’s what’s forcing Outlook to keep prompting for it.
Go to Settings → Accounts → Access work or school, look for any listed work/school account (even if it looks inactive or unfamiliar), select it, and click Disconnect. After removing it, restart your computer, then open Outlook again and sign in using only your personal Microsoft account.
If the account does not appear there but the issue persists, also check Settings → Accounts → Email & accounts and remove any work/school entries listed under accounts used by other apps.