If you want to change a user’s email address, then it’s fairly difficult if email isn’t working.
Your problem, which exists only because your forum is broken and cannot send email, is that you cannot log in as some admin user you have created already, right?
You can set the password for that user (or any user, admin or not) using admin user:create, so you don’t need to get an email to verify the account.
If what you want to do is change that particular admin’s email address, you should just wait until email works.