Open your account settings by tapping on the cog wheel icon (⚙) in the upper-right corner of the ME screen. From this view you can change your email address.
To change your email address, simply tap on the edit (pencil/paper) icon and enter the new email address. Please note that each Sanvello account must have a unique email address. If your email address is currently in use for another Sanvello account, you will not be able to re-use it or merge accounts.