It is not possible to cancel a pick released order line if there are processing constraint which have been enabled to prevent this from happening.

There are two methods that can be used to.

OPTION 1

1. Disable all processing constraints that prevent you from cancelling the line

The following SQL can be used to identify these.

SELECT   condition_id,
         validation_entity_display_name,
         b.column_name,
         user_message,
         a.enabled_flag,
         a.system_flag
    FROM oe_pc_constraint_cnds_v a,
    OE_PC_CONSTRAINTS b
WHERE upper(user_message) like '%CONFIRMED/STAGE%'
   AND a.constraint_id = b.constraint_id
ORDER BY validation_entity_display_name,
         column_name;

NB -NB: Though this is a feasible solution great care must be taken as this may affect you business rules.

OPTION 2 (recommended approach)

Backorder the lines and then cancel them. This can be done by:

1. Navigate to the shipping transaction form and query the order.

2. Select the line and enter 0 at shipped quantity

3. Save the record

4. Ship confirm the line, this will cause the line to be backordered.

5. Query the order line in the order entry form and cancel this.