The SETUNI DELETE command can be used to delete specific conversions from the z/OS Unicode environment. Deleting conversions data is not recommended except when it is necessary to perform maintenance (such as activating a PTF) without an IPL.

When a conversion is deleted, the control block that anchors that conversion data is changed to indicate that the specified conversion is not present. The conversion data itself is not removed. The z/OS Unicode environment's date stamp is updated, so any handles that refer to the deleted conversion become invalid. (All handles become invalid.)

There is no synchronization between conversions that are using conversion data and the function that deletes conversion data. Any conversions that are using the conversion data at the same time it is being deleted continue running normally until they find out their conversion handle has become invalid. This situation is then handled by the "handle validation" flags in the parameter area.