Mail Account appears twice

Hi,

I have created an email account in Mail App with my Hotmail.
Now, when I open Mail App and look at the Settings, the list at the top shows twice the same Hotmail account.
I tried to delete one of them, but the Delete Account button is grey out.
I looked at PC Settings / Users and I see only one Hotmail account

Also, I don't know if it is related, but Calendar App doesn't work.
I click on the icon, and it open and close automatically.

I don't know what to do to solve my problem. Any help will be appreciated.