How to disable authentication when exposing interfaces as web service

Hi experts,

I have a perculiar question:

I have a synchronous interface:

SOAP -> XI -> RFC --> XI -> SOAP

I generated the WSDL by using Integration Directory -> Tools -> Define Web Service.

Normally, I can invoke the webservice using SOAP Client, but I have to enter the userid/pwd. - PIAPPLUSER.

My question is:

How do I disable the authentication?

Please help.

Thanks.

Ron