Have a weird issue with outlook

[Punisher]

Whenever I open outlook on the PC it keeps asking for a password for an account that doesn't exist.
Ex.
I have 2 real accounts. Say Punisher1 and Punisher2. They login fine and send and receive fine. Then it pops up asking for the password to FrankCastle which doesn't/shouldn't exist.
I triple checked the email accounts lusted in Outlook and the only ones l7sted on each tab are Punisher1 and Punisher2.
I also check credential manager, work accounts or connections and some other th8ngs that I forgot to write diwn so I also firget them completely..
Any ideas?
If someone posts something that jogs my memory I'll let you know.

[Carpet_pissr]

Do you have an online Outlook/Live/Hotmail account that you’ve forgotten maybe?

[Punisher]

Can't remember for sure but I dont think I'd have one wirh a user name that shows up. It's my first initial last name, FCastle for example.
I think I had that for my old job but don't think I used it on this laptop and I think IIRC that we used gmail.
How would I check?