Mass delete Drupal Commerce Coupons
The code below should do the trick. If you have Devel installed, just open the devel/php page and execute this:

// Get all coupons on the site.
$coupons = db_select('commerce_coupon', 'c')
  -&gt;fields('c', array('coupon_id'))
  -&gt;execute();

// We will store here all coupon IDs, so we can delete them at once.
$coupon_ids = array();
foreach ($coupons as $coupon) {
  $coupon_ids[] = $coupon-&gt;coupon_id;
}

commerce_coupon_delete_multiple($coupon_ids);