How do I remove my primary email from Apple ID?

I'm not understanding what you want to do exactly. The support article Change your Apple ID - Apple Support outlines various methods for changing the email address (Apple ID) you use for your Apple Account while retaining everything in your account.

If instead you are referring to your primary iCloud Mail address, you cannot delete or change that. You can uses aliases instead. Add and manage email aliases for iCloud Mail on iCloud.com - Apple Support - "An email alias is an email address that conceals your actual email address from a recipient. An alias can help you manage the email you receive, and monitor the sources of unwanted messages. You can both send and receive email from an email alias using Mail on iCloud.com.