Not sure how to turn it off but the language file is incorrect that is why it is not clickable.
I just noticed it myself.
cp>> languages.language editor
Choose Specific Language File: mailer.php
Find VER_EMAIL_CONTENT key field.
For my version it is at the very bottom of the page
Here is what I have in mine
A request has been made to update your email address to %%EMAIL%%. In order for us to continue with this change, you'll need to visit the link below to validate the email:<a href="%%VERIFY_URL%%">link</a>