how do i change my apple id from phone number to email?

I don't think you can do that. From the article below.

In some countries or regions, you can use your phone number as your Apple ID. But if your Apple ID is an email address, you can't change it to a phone number.

If your Apple ID is a phone number

You can change your Apple ID to a different mobile phone number.

Change your Apple ID - Apple Support

I've seen this question asked many time. I know how to do the reverse of what you want. But, I have never seen Apple, etc., guidance on doing what you want to do.