SOLUTION!!! This worked.
The last step, step 5, where it says to delete all the files. DELETE EVERYTHING. Files AND folders.
I had no files, but I had folders. So I left the folder untouched, but it didn't work.
And then when I opened New Outlook again, the files from step 3 and 4 came back. So at least I knew we were on the right track.
So I closed New Outlook again, did step 3 and 4 again, and this time, for step 5, I deleted the single folder that I had left untouched. The folder had a bunch of subfolders too, so all that was deleted. and now that entire directory was CLEAR.
Opened New Outlook and VIOLA! (Kelly Bundy reference), my email address was no longer in selected accounts.
Finally, SUCCESS!
https://www.slipstick.com/new-outlook/removing-suggested-accounts-outlook/
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SO, to round this all out. (this is what I did)
Make sure you log out of your account in windows settings. Remove it from your Windows account, etc. etc.
Make sure you log out of the Microsoft Store
Then, do the instructions in the link above.
I will actually now copy and paste those instructions here JUST IN CASE one day that site goes down
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Step 1:
Close new Outlook. If it is running when you do the following steps, the addresses won't be removed.
Step 2:
Remove the accounts from Windows Settings > Accounts. Look under Email and under Work or School accounts. Remove or disconnect the accounts. Note: removing accounts here will sign you out of the account in Office and OneDrive.
Step 3:
After removing the accounts from Windows Settings, you need to delete the contents of this folder:
C:\Users\%username%\AppData\Local\Microsoft\OneAuth\blobs
Step 4:
Using Notepad, open each file in the following folder. Look for the email address for the account you want to remove. When you find a file with the address in it, delete the file.
C:\Users\%username%\AppData\Local\Microsoft\OneAuth\accounts
Step 5:
Finally, delete all the files AND FOLDERS* in this folder:
C:\Users\%username%\AppData\Local\Microsoft\IdentityCache
Step 6:
Open new Outlook and open the Add account dialog.
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Let me know if this worked or not, I'll help you find the solution.
Marco