You cannot directly change the name of a UDF that performs the role of a transform, ordering, or cast for a UDT.
You must first drop the corresponding transform, ordering, or cast definitions. Then, rename the UDT. To drop an ordering or a transform, see DROP ORDERING or DROP TRANSFORM. To drop a cast, see Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144.