In Netscape, poke around the menus at the top, look for settings/preferences (I think preferences). You should be able to locate something about it there.
Hopefully a more knowledgeable member will post a Netscape answer before you must resort to that, however :)
In Netscape 7.0, goto Tools, cookie manager, Manage stored cookies, one of the tabs you will see is "stored cookies." Either highlight the cookies you want to loose and click "remove cookie" or click "remove all cookies."
The other tab is for blocked cookie sites. You may want to leave those in place or, if a site needs a cookie and you have blocked it, you can remove it here allowing the site to work again.
Fastest way to del them all!
Click on start then locate find in the strat menu, got it! Now type in cookie then cntrl a for select all then hit delete button.
Youve done it, alls erased.