If you need to change the email address associated with your account in Hull, you'll need to invite the new email address to your Hull account. To do this, access your Hull Organization Settings, as shown below.
Simply enter your new email address and click "Invite".
Finally, select the the new email address and assign the desired role. If you are the owner of the account and intend to transfer ownership to the new email address, select the "Owner" role.
You can then remove your original address after ownership has been transferred, if needed.