[tsac]

if your talking about the password on the phone and not just the email service then simply enter the password wrong until it asks you to enter Blackberry. It will then go a couple more times and do a complete wipe and reset to factory.
This will allow you to do a new setup including entering a new email address and password .
If your taking about the email provided by the carrier then most have a site where users can log into and reset or change the password on email different from the user login for the support site.
Telus offers support if it's their email address. go to their web site.