I want to delete my account from the thunderbird server so that I can start fresh on ubuntu. I have forgotten my password on the old account.

I have forgotten my password and even my username in Thunderbird mail. When I try to get a new password, they send it by email. Since I cannot get into email I do not get the code. I want to completely remove my account from the server so I can start fresh. This takes me to username and email + password. I enter the new details and the server having not deleted my account sends, "Incorrect email or password. This is why I want to delete it completely so I can really start a fresh setup. I am using Ubuntu 2404. Thank you for your help. Rod.