After you have picked the items, packing requests will be orders been picked in the Picking step How to manage the Picking step in your warehouse with RMS, they will be moved to Packing step with packing requests created for each order.
You can access the Packing Request list by Menu → Fulfillment → Fulfillment Management → Packing.
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You can learn how to pack items with RMS system in this article: How to pack items with RMS Packing Request list
When there is a packing request that you want to cancel, you can follow the step in How to cancel a Packing Request