Deleting a Function 
Use caution when you delete a function. You must first remove the function from any existing risk before you delete it.
Procedure
To delete a function:
Navigate to
Rule Architect 
Functions Search 
The Search Functions screen appears.
Search for the function you want to delete. You can refer to the topic Viewing a Function, for instructions to find the function that you want to delete.
Once you find the function, select the check box next to it, and choose Delete.
A confirmation message appears.
Choose OK.