You can change the email address associated with your account through your account settings.
Intuit uses a single sign in system for all Intuit products, so changing it here will also update it for any other Intuit products you use, such as QuickBooks or Credit Karma.
If you can't sign in at all, you can go to the Intuit Account Recovery page. This requires you to upload a photo of a government-issued ID to verify your identity.
Here are two FAQs to help: What if I'm having trouble with my filing verification code? and How do I get a verification code if the email address is wrong?