You should cancel an order inside your sales channel (Shopify, Amazon, etc).
Cancellation in Sales Channel:
Notifies the customer.
Allows processing refunds
Automatically reflects the cancellation status in SKULabs after the next order sync.
Does not automatically void labels or restore inventory
Cancellation in SKULabs
Does not notify the customer
Does not have a way to process refunds.
Does not update the status on the sales channel.
Does not automatically void labels or restore inventory
In both cases when SKULabs knows an order is cancelled in either site we will warn pickers trying to create a shipping label for the order and otherwise discourage mistaken processing of the cancelled order.
Voiding labels and restoring inventory for prior shipments
If you've already created a shipping label for a cancelled order, you will need to pull the package from the staging area in your warehouse and void the label manually. View your archived tab for cancelled orders with "# of shipments" above zero to find your cancelled orders with shipments.
If you use scan based deduction, make sure to create an RMA on the order to ensure that you have received orders stock properly back into your inventory.
Tip: Use the "View [Amazon] Order" link in the order's menu to quickly find the order on your store from within SKULabs.