If a supporter needs to transfer ownership of their fundraising page to another person (friend, family member, etc.), you can edit the page's owner from the admin section.
This is also useful if supporters need to change their email addresses, as this can be done by moving the fundraiser to a new owner with that email (but the same name).
To do this, go to administration --> fundraisers --> search for fundraiser --> choose "Change owner"
In the pop-up, you can now edit the owner's first name, last name, and email.