Hide coupon code for students

add_filter( 'woocommerce_coupons_enabled', 'disable_coupon_field_student' );
function disable_coupon_field_student( $enabled ) {
     if ( in_array( 'administrator', (array) $user->roles ) || in_array( 'Student', (array) $user->roles ) || in_array( 'shop_manager', (array) $user->roles )) {
        $enabled = false;
    }
    return $enabled;
}