uninstall.php

<?php

$sql = rex_sql::factory();

// Delete url schemes
if (\rex_addon::get('url')->isAvailable()) {
    $sql->setQuery('DELETE FROM '. \rex::getTablePrefix() ."url_generator_profile WHERE `namespace` = 'course_id';");
    $sql->setQuery('DELETE FROM '. \rex::getTablePrefix() ."url_generator_profile WHERE `namespace` = 'courses_category_id';");
}

// Delete views
$sql->setQuery('DROP VIEW IF EXISTS ' . \rex::getTablePrefix() . 'd2u_courses_url_categories');
$sql->setQuery('DROP VIEW IF EXISTS ' . \rex::getTablePrefix() . 'd2u_courses_url_courses');

// Delete tables
$sql->setQuery('DROP TABLE IF EXISTS ' . \rex::getTablePrefix() . 'd2u_courses_categories');
$sql->setQuery('DROP TABLE IF EXISTS ' . \rex::getTablePrefix() . 'd2u_courses_2_categories');
$sql->setQuery('DROP TABLE IF EXISTS ' . \rex::getTablePrefix() . 'd2u_courses_courses');

// Delete language replacements
if (!class_exists(TobiasKrais\D2UCourses\LangHelper::class)) {
    // Load class in case addon is deactivated
    require_once 'lib/LangHelper.php';
}
TobiasKrais\D2UCourses\LangHelper::factory()->uninstall();