Inventory Planner is mostly read only service. We don't create/edit/remove any products or sales orders.
For e-commerce platforms such as Shopify, BigCommerce and others, you can optionally update stock quantities when you mark your products as received in purchase orders. This step is explicit and cannot be done by accident.
For inventory management systems such as TradeGecko, Ordoro, BrightPearl, or Vend we push purchase orders to these platforms when they are created on Inventory Planner.