The Email field is part of the SDK Wrap-up screen. It's optional and allows your users to leave their email address with the report they're submitting.
Hide the Email field
Use the following method if you don't want to show this field in the SDK:
Pre-fill the Email field
Use the following method to save your users some time by pre-filling the field with their email address (users can always edit or delete that email if they want to):
Do you want to make sure you always receive user's email with a report? You should then both pre-fill and hide the Email field.