Make e-Mail optional on Woocommerce sign up

My site uses mobile login ability and that is our primary means of communication and the brick and mortar utilised this so we need to make it optional for users to enter email as we have a local sms system anyway for passwords as each customer has to validate their details first in store with in. Majority of users will use mobile not email. Tried a bunch of codes but still nothing including making it not required , need it not required on billing, registering (right now login with phone works). For billing I’ve tried

add_action( 'woocommerce_register_form', 'wooc_email', 15 );
function wooc_email() {
    if( $key == 'billing_email'  ){
                $registration_fields['billing_email']['custom_attributes'] = array('required'=>'false');
            }
}

For registration tried a few but nothing came of it and thus no code.

I know the registration process is same as WP.

Any and all help useful.