How do I reset AppleID when it’s linked to an email account that no longer exists and I’ve forgotten the password?

The only option that you have is to enroll in account recovery

How to use account recovery when you can’t reset your Apple ID password - Apple Support

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (go to this document: How to use account recovery when you can’t reset your Apple ID password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.

One tip to using account recovery it to look for options in small blue letters beneath the normal log-in items if you cannot complete the requested information.