autofill

HI we got a internal site which pops up a window to autofill username/password. That page is made in jsp. Now i got a php script to get the data from that site. Problem is i need to bypass the pop window or else it gives me auth errors. I already have username/password with me.

Whenever i fill online forms, user ids, email adds. it get stored. By filling again it shows what ids are used here. I want to remove autofill from textbox. how to do this. can any one explain.??????