The target data type from the cast definition.
Either target_data_type or source_data_type or both must be a UDT.
Example: Dropping the System-Generated Cast from Source Data Type to Distinct UDT
The following example drops the system-generated cast of DECIMAL to the UDT euro.
DROP CAST (DECIMAL AS euro);
Example: Dropping the System-Generated Cast from Distinct UDT to Source Data Type
The following example drops the system-generated cast of UDT euro to DECIMAL.
DROP CAST (euro AS DECIMAL);