Hi @jcw
Normally you would not need to confirm your login email to update it unless you never did so when starting LastPass.
If you cannot reset the email account password, you will need to contact LastPass Support to confirm your identity, and then we will confirm the IP/device trying to log in. This will require you to start a new trial under the new email address so we can communicate securely.
Pleaseuse the 'Request help' button within the Email Verification support article, and use the new LastPass account email address to create an email case.
Once the original login has been permitted by the system, you can then delete the new account and change the login email of the original account via email verification (sent to the updated address).