I can't seem to edit the recipient email address for my contact form.

When I go to settings for the contact form, click on emails in the left hand column, and try to edit Notification 1 (the recipients), it allows me to remove an email address, but not replace it with a new one. I really want to replace one of these email addresses for a client (and not have to upgrade my account- why should I have to, just to change an email address?). Can someone please help? 

This is a limit in the FREE account. You can only have one Recipient Email for each Notification.

If you want to have another recipient for the email submission on FREE account, you can just duplicate the notifier and then assigned a new recipient email.

Paid account do allow multiple email recipients.