There are two ways to cancel a Listing:

1) From the  Inventory page, click Change Status for the inventory record you want to cancel.

Once you click on Change Status, the box below will appear.  Choose Cancelled and confirm your choice by clicking Save.

2)  From the  Documents page of the Inventory tab, click the Cancel Listing button, as displayed below.

The confirmation message below will appear, select Yes to confirm you want to cancel the listing.