Replace
SELECT p.products_id as pID, p.products_date_added as date_added, p.products_last_modified as last_mod, p.products_ordered
FROM products p, categories c, products_to_categories p2c
where c.categories_status='1' and p.products_id = p2c.products_id and p2c.categories_id = c.categories_id and p.products_status='1'
ORDER BY products_ordered DESC
To
SELECT p.products_id as pID, p.products_date_added as date_added, p.products_last_modified as last_mod, p.products_ordered
FROM products p, categories c, products_to_categories p2c
where p.products_id = p2c.products_id and p2c.categories_id = c.categories_id and p.products_status='1'
ORDER BY products_ordered DESC
Alternatively, install enable/disable categories