You want to delete an Item Type but it's used in a Sales Order. You cancel the sales order but it declines due to the status of the sales order being Complete.
Reproducing the Issue
1. In Business Configuration, find activity Sales Orders
2. click Maintain Item Types
3. select the Item Type you want to delete and click the Delete button
-> Item Type cannot be deleted because it is being used in a sales order. This sales order is cancelled however.
An Item type which is being used by a sales order cannot be deleted, even if the sales order is cancelled.
This is the expected system behaviour.
KBA , SRD-FIN-GL , General Ledger , How To