I had a Gmail account configured in Kmail that all of a sudden went offline and there was nothing I could do to make it go online again. I deleted the account and set up a new Gmail account, that works fine. The old account, however, is still shown (as "offline") in the list of the accounts in the panel on the left of the main window of Kmail, and I cannot manage to delete it. I also tried to uninstall kmail, but I could not find the configuration file in my home directory, so when I installed it back the old broken account is still shown. Any suggestion?

I found a command line workaround and I managed to clean all the Kmail settings: https://docs.kde.org/trunk5/en/pim/kmai ... ation.html. This deleted all the accounts but the local folder, so I had to configure everything from scratch, but solved the problem!