How do i change my apple id address

1. Go to Settings, then tap your name. 
2. Tap Sign In & Security. 
3. Next to Email & Phone Numbers, tap Edit. 
4. Tap the Remove button next to the email address, then tap Delete. 
5. Tap Choose Another Email Address and enter your device passcode if asked.
6. Enter the new email address, then tap Continue.
7. Enter the verification code that was sent to your new email address. 

See the instructions above on how to change your Apple ID

Here's how you change the email address (Apple ID) you use for your Apple Account while retaining everything in your account:

1. Go to https://appleid.apple.com and sign in.

2. In the Sign-In and Security section, choose Apple ID.

3. Enter the email address that you want to use as your Apple ID.

4. Choose Change Apple ID.

5. If you changed your Apple ID to a third-party email address, check your old ID email for a verification code, then enter the code. Learn what to do if you didn't get the email. --> If you didn't receive your verification or reset email - Apple Support

6. If you encounter issues with certain services after doing this, this outdated support article may still have useful suggestions --> What to do after you change your Apple ID or password - Apple Support

For more details, read the document: "Change your Apple ID" --> Change your Apple ID - Apple Support

I note the different statements about checking your email address for a verification code in step 7 in the new version of the article and step 5 in the one I posted which is from a slightly older version. I would say you should probably check both places. (I think sending it to the old address is a more secure method of ensuring it is the true owner of the account doing this.)