Clearing a text box and hidden box

In asp source code i am using onClick () on ie textbox

onClick="openpopup('ct100$contentPlaceHolder$hdpackageid',
           'ct100$contentPlaceHolder$txtpackageid','package')" 

      

        
        
        
      

    

to open a pop-up window with detailed information about the package. And in its selection in the popup, the packageid is stored in the hidden field and the packagename is stored in the textbox. I need to clear hidden field and textbox after selection if I don't need it. I am using "this.blur ();" for not editing the text box. I need these things to be written to the vb code, which means in onClick I want to clear the textbox, hidden field and then trigger the popup. Can anyone help me solve the problem. Is there any other way to do this?