Change your login email address

Click [Your name] in the upper right corner of the chat screen, then click [Account Settings] → [User Information] → click  [Change] button of Email address.

Then insert the email address you want to register for your [Email Address] and click the [Save] button to save the change.
 

Change your email address for your profile

Click [Your name] in the upper right corner of the chat screen, then click [Profile] → [Edit profiles] to change your email address. 
Click here to view the steps.