We have tested the queries below in :
WooCommerce version: 3.5.7
WordPress version: 5.1.1
( Use at own risk )
=======================
Delete all orders woocommerce
DELETE FROM wp_woocommerce_order_itemmeta;
DELETE FROM wp_woocommerce_order_items;
DELETE FROM wp_comments WHERE comment_type = 'order_note';
DELETE FROM wp_postmeta WHERE post_id IN ( SELECT ID FROM wp_posts WHERE post_type = 'shop_order' );
DELETE FROM wp_posts WHERE post_type = 'shop_order';
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delete all products
DELETE relations., taxes., terms.*
FROM wp_term_relationships AS relations
INNER JOIN wp_term_taxonomy AS taxes
ON relations.term_taxonomy_id=taxes.term_taxonomy_id
INNER JOIN wp_terms AS terms
ON taxes.term_id=terms.term_id
WHERE object_id IN (SELECT ID FROM wp_posts WHERE post_type='product');
DELETE FROM wp_postmeta WHERE post_id IN (SELECT ID FROM wp_posts WHERE post_type = 'product');
DELETE FROM wp_posts WHERE post_type = 'product';
==========================
Remove all attributes from WooCommerce
DELETE FROM wp_terms WHERE term_id IN (SELECT term_id FROM wp_term_taxonomy WHERE taxonomy LIKE 'pa_%');
DELETE FROM wp_term_taxonomy WHERE taxonomy LIKE 'pa_%';
DELETE FROM wp_term_relationships WHERE term_taxonomy_id not IN (SELECT term_taxonomy_id FROM wp_term_taxonomy);
==========================
Delete all WooCommerce products (2)
DELETE FROM wp_term_relationships WHERE object_id IN (SELECT ID FROM wp_posts WHERE post_type IN ('product','product_variation'));
DELETE FROM wp_postmeta WHERE post_id IN (SELECT ID FROM wp_posts WHERE post_type IN ('product','product_variation'));
DELETE FROM wp_posts WHERE post_type IN ('product','product_variation');
==========================
Delete orphaned postmeta
DELETE pm
FROM wp_postmeta pm
LEFT JOIN wp_posts wp ON wp.ID = pm.post_id
WHERE wp.ID IS NULL;
==========================
delete all categories
DELETE a,c FROM wp_terms AS a
LEFT JOIN wp_term_taxonomy AS c ON a.term_id = c.term_id
LEFT JOIN wp_term_relationships AS b ON b.term_taxonomy_id = c.term_taxonomy_id
WHERE c.taxonomy = 'product_tag';
DELETE a,c FROM wp_terms AS a
LEFT JOIN wp_term_taxonomy AS c ON a.term_id = c.term_id
LEFT JOIN wp_term_relationships AS b ON b.term_taxonomy_id = c.term_taxonomy_id
WHERE c.taxonomy = 'product_cat';
==========================
Delete alle WooCommerce customers / Users
You Can delete alle WooCommerce customers / users with this plugin :
Bulk Delete