A quick hack to destroy all sample data in an OpenCart catalog.

destroy-sample-data.php

<?php 

$options = getopt('p:');
$prefix = empty($options['p']) 
    ? realpath('.')
    : realpath($options['p']);

if (empty($prefix)) {
    die("Bad prefix. Try again.\n");
}

require $prefix . '/admin/config.php';
require $prefix . '/system/database/' . DB_DRIVER . '.php';
require $prefix . '/system/library/db.php';

$db = new DB(DB_DRIVER, DB_HOSTNAME, DB_USERNAME, DB_PASSWORD, DB_DATABASE);
$tables = array(
    'address',
    'category',
    'category_description',
    'category_to_store',
    'coupon',
    'customer',
    'download',
    'download_description',
    'manufacturer',
    'manufacturer_to_store',
    'product',
    'product_description',
    'product_discount',
    'product_featured',
    'product_image',
    'product_option',
    'product_option_description',
    'product_option_value',
    'product_option_value_description',
    'product_related',
    'product_special',
    'product_to_download',
    'product_to_store',
    'review',
    'store',
    'store_description',
    'product_tags',
    'order',
    'order_download',
    'order_history',
    'order_option',
    'order_product',
    'order_status',
    'order_total',
    'product_to_category',
    'coupon_description',
    'coupon_product',
);

foreach ($tables as $table) {
    $sql = sprintf('TRUNCATE TABLE %s%s', DB_PREFIX, $table);
    printf('%s %s ', $sql, str_repeat('.', 73 - strlen($sql)));
    $db->query($sql);
    echo "Done!\n";
}

My version Opencart V 3.0.1.1:
TRUNCATE TABLE oc_product;
TRUNCATE TABLE oc_address;
TRUNCATE TABLE oc_category;
TRUNCATE TABLE oc_category_description;
TRUNCATE TABLE oc_category_to_store;
TRUNCATE TABLE oc_coupon;
TRUNCATE TABLE oc_customer;
TRUNCATE TABLE oc_download;
TRUNCATE TABLE oc_download_description;
TRUNCATE TABLE oc_manufacturer;
TRUNCATE TABLE oc_manufacturer_to_store;
TRUNCATE TABLE oc_product;
TRUNCATE TABLE oc_product_description;
TRUNCATE TABLE oc_product_discount;
TRUNCATE TABLE oc_product_image;
TRUNCATE TABLE oc_product_option;
TRUNCATE TABLE oc_product_option_value;
TRUNCATE TABLE oc_product_related;
TRUNCATE TABLE oc_product_special;
TRUNCATE TABLE oc_product_to_download;
TRUNCATE TABLE oc_product_to_store;
TRUNCATE TABLE oc_review;
TRUNCATE TABLE oc_store;
TRUNCATE TABLE oc_order;
TRUNCATE TABLE oc_order_history;
TRUNCATE TABLE oc_order_option;
TRUNCATE TABLE oc_order_product;
TRUNCATE TABLE oc_order_status;
TRUNCATE TABLE oc_order_total;
TRUNCATE TABLE oc_product_to_category;
TRUNCATE TABLE oc_coupon_product;
truncate table oc_seo_url;
truncate table oc_product_reward;
truncate table oc_product_attribute;
truncate table oc_category_path;
truncate table oc_banner_image;
truncate table oc_banner;
truncate table oc_attribute_group_description;
truncate table oc_attribute_group;
truncate table oc_attribute_description;
truncate table oc_attribute;

Thanks for sharing this code works well