My iCloud is connected to an old email address

See this article macOS Sierra: Change iCloud account information

1. Choose Apple menu > System Preferences, click iCloud, then click Account Details.
2. 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.
   • 
3. See this article Change your Apple ID - Apple Support

Greetings, mariephilp.

I see that you'd like to use a different email address for your Apple ID, and I'm happy to help.

Change your Apple ID -- If you haven't already created a new ID, these are the steps to change the email address that's being used on your current Apple ID..

What to do after you change your Apple ID or password -- Once you've changed the email account, you'll need to sign out of the old ID and sign into the updated ID in the Apple services you use. This article provides of list of Apple services.

Take care!

What happens when you try to sign out of the old address? Error message(s)?