Yes, if the request is not received then the user him/herself can change the reference to another person. Below are the steps to update the recommender email id.
Steps to update recommender email id:-
1) log in to the site.
2) Click on the Application name from the My Application tab.
3) Click on the Request section icon.
4) Click on the Request section Form.
5) Click Ok on the "Are you sure you want to resubmit this request?" pop up screen.
6) Enter the correct email and click on Email Request.
Note: If the request is received then the admin need to rerelease that section to the user so that they can change the request.