E-Mail client: unable to delete an account

A few weeks ago I added a 2nd mail account to the E-Mail client to check for incoming mails wherever I’m currently are. Now I want to delete this account but that’s not possible. The deleted account appears again and again and again … This is especially annoying because it’s a high traffic account. How to finally delete this?
Oh, and another question, unrelated to the first one: I have one of the older murena one phones with Android 10. Any chances to get Android 11?

Regain your privacy! Adopt /e/ the unGoogled mobile OS and online servicesphone

what is your version string that you’re on?

How can I reproduce the behaviour, how long would I need to wait until the deleted account reappears? In the current Mail within v1.5 I can’t reproduce the resurrection of a removed mail account.

The development-updates thread says murena one can be had currently up to R (11), and Android S (12) will be in the works. Isn’t there only one versions of the Murena One? excuse the naive question