DeleteAllUserContacts()
From Rackspace Email & Apps API
This function will remove all contacts from a user's address book.
Input Parameters
Four strings and a result integer
Administrative username, Administrative password, Domain name, User ID (the portion of the email address before the @ symbol),
Result integer
Return Values
If successful, the return value of the function will be 1.
Consult the Result Code Table for a list of result codes and their meaning.