This clause is used to drop a method signature associated with the specified UDT from the definition of that UDT. This is the only way you can drop a method. There is no DROP METHOD statement.
If you do not specify a method type, the default type is INSTANCE.
You cannot drop observer or mutator methods from a UDT definition.
When you drop a method signature from a UDT definition, the system also destroys its associated external routines.
However, when you attempt to execute any of the affected database objects, the system returns an error to the requestor.
The ANSI SQL standard does not permit you to drop methods from a distinct UDT definition; however, you can drop methods from distinct UDTs as a Teradata extension to the ANSI SQL:2011 standard.
To replace the external routine for a method, use the REPLACE METHOD statement (see REPLACE METHOD and Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144).