You can easily change the email address of the user that you have sent the document to. To do this:
Open up the document that you would like to amend
Click on the 'Add User' button on the left of the screen under the 'Parties' tab under the person you would like to change.
3. From here you can change the email address and press 'Submit'. You can also add another user to the document at this stage by pressing the 'Add User' button if needed