You definitely selected the "delete" char option. There is no other place where it asks the password confirmation.
When you click on the delete button there is a pop-up with this text:
"Warning! this will PERMANENTLY DELETE your character. Are you sure you want to continue?"
If you click on "Yes" it will then ask your password for confirmation. I think it's very explicit already.
I checked the backups, there is a backup of the 16th September where this char is still present. The issue is restoring data is not very simple, as the db dump is various GB of data, and requires us to restore it entirely on a separate DB, then do the dump somehow manually. So basically it's a lot of work.
The char has 35 hours of gameplay.