problem with cfcookie

Hi

I have some problem with cfcookie.

No where CFCOOKIE tag or javascript fns are used to create  a cookie from the code. But cookies are created ans stored in the local system once logged into appln. By default expire value displayed for the cookie file is30yrs from nowI.e.,1/5/2044.

please suggest me some solution to delete the cookie file from client mechine on session time out or browser close.

please find the detaiils of my cfapplication tag

<cfapplication name="xxxxxx" clientmanagement="yes" setclientcookies="yes" scriptprotect="all" clientstorage="Cookie">

Thanks in advance

kalyani.