How can I get rid of all my email accounts from my sons iphone

Is your son's phone on the same Apple ID as your Apple ID? If it is, he should have his own Apple ID.

1. Ensure that your son has his OWN Apple ID. Make sure both of you are NOT using the same Apple ID.
2. Once the above is confirmed or completed then add him to Family Sharing organized by you.
3. The above will ensure that your son does not get your texts, pictures, contacts, notes etc.

Axel F.