See -> About your Apple ID email addresses
About your Apple ID email addresses - Apple Support
I want to change my email address for Apple because I don’t I’m use it at all.
How can I change it to my primary email address?
That is not possible.
Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.
You can’t merge multiple Apple ID accounts.
See the following Apple articles
Sign in with your Apple ID -> Sign in with your Apple ID - Apple Support
Manage and use your Apple ID -> Manage and use your Apple ID – Apple Support (UK)
If you still need help, get support from Apple directly -> Get Support or call Apple in your region see -> Contact Apple for support and service