1. Preferences (or whatever the Windows equivalent is--Opitions?) > Advanced > Content Settings 2. Click the All Cookies and Site Data button 3. In the Search Cookies search bar, type "insanejournal.com" 4. Select and remove those cookies 5. Close out all the dialogs and windows until you're back to the main screen
That should get rid of all the cookies. Don't be alarmed that there are a zillion cookies; IJ generates a cookie for every journal you visit. That's normal.