This article explains how to mark item cards inactive.
Steps in Xero:
Mark item as inactive
Add “zz” to the beginning of the Item Name
Steps in WMS:
During replication, if WMS finds any Xero items that start with zz, this is a trigger for WMS to mark the item as inactive in WMS.
Settings to Show or Hide Inactive cards from the registers can be managed via Inventory Preferences.
There is a known/current issue with the Xero API where it does not show if an item is Active or Inactive.