I can't remember my iTunes password and the email it's tied to is no longer active
You can contact Apple via Apple Support. Select "More Products and Services" followed by "Apple ID". On the following page you asked to choose a topic, select "Other Apple ID Topics" followed by "Lost or Forgotten Apple ID Password". You will then be asked if you would like an Apple support specialist to contact you, or if you would like to schedule a call at a later date.

I suspect they are going to ask you a series of billing related questions to verify your identity. If they are able to verify your identity, you should be able to provide them an alternate email for the password reset link. 

Good Luck :)