If you have an existing user defined function that you don't want to use it anymore, you should delete it from the SQL Server by using the "DROP FUNCTION" statement as shown in the tutorial example below:

USE GlobalGuideLineDatabase;

GO

DROP FUNCTION Welcome;

GO

Command(s) completed successfully.

SELECT * FROM sys.objects WHERE type_desc LIKE '%FUNCTION';

GO

name  object_id schema_id type type_desc  

-------- ----------- ---------- ---- -------------------

Sundays 2117582582 1  FN SQL_SCALAR_FUNCTION

(1 row(s) affected)

User defined function "Welcome" is no longer in the database.