- is coming from user with ID one. That is the system user by default.
You can technically rename the display name of that account, however, please note that this affects all places within Zammad. It also affects owner selections which will be confusing.
Easiest way is to do the rename via API or console, here’s the console way:
zammad run rails r "p User.find(1).update(firstname: 'Evil', lastname: 'Zammad')".
Keep in mind that you have to provide first- and lastname.