How to update customer contact email in bulk

We are trying to mass update customer contact email address at site level but not sure which FBDI file or API to use.

Looking out for any guidance with regards to the same.

I have looked at customer import template but not sure which all fields need to be entered in order to update the email.

Also, for some of the cases, we need to delete the email which I believe is not possible and rather will have to end date the contact point if I am able to use the customer import template.