Factor ID

I no longer have access to the email that I have used for my Apple ID. I didn’t need it and couldn’t figure out how to change my id so I just left it. Now, I need to access my granddaughter’s calendar and it wants my Apple ID. I gave it but it sent a code to the email I no longer have access to. Usually when I get some kind of code it goes to my phone, but now it has gone to this old email. I tried to change my id but it says my email is invalid. I don’t know what to do. Can you help me?