If you’ve set up an Apple ID in macOS Sierra, but need to change the email address associated with it, it's an easy procedure. In fact, you can change your iCloud name and photo, and your iCloud contact, security, devices, and payment information in iCloud preferences.
To change contact information, choose Apple menu > System Preferences, click iCloud, then click Account Details. Click Contact, then view or change the following:
- Email addresses: Add and remove email addresses and phone numbers associated with your iCloud account. Friends and family can use these to share notes and documents with you, and reach you using iMessage, FaceTime, Game Center, and more.
- Primary address: Change the mailing address for your iCloud account.
- Email preferences: Select the kinds of information you want Apple to send to your iCloud email addresses.