matador-default-required-fields

function matador_default_required_fields( $fields ) {
	return   array(
		'first_and_last_name',
		'email',
		'phone',
	);
}
add_filter( 'matador_default_required_fields', 'matador_default_required_fields' );

// or

function matador_default_required_fields( $fields ) {
	// add phone
	$fields[] = 'phone';
	
	// find the key and then unset it
	if (($key = array_search('resume', $fields)) !== false) {
		unset($fields[$key]);
	}

	return $fields;
}
add_filter( 'matador_default_required_fields', 'matador_default_required_fields' );