Hi all, 

I have recently reinstalled the Mail and Calendar app since they were crashing. I do not know (remember) how one of my "Yahoo" accounts ended up there, where it can be seen in Mail and Calendar apps but not in the Settings below the Accounts section. 

In short: 

I can not remove it, when I click on it, a small window pops up and closes immediately. I can not find it in Settings > Accounts. 

How to remove or fix this account?