How to clear cookies
in Mozilla Firefox, posted Oct 23rd 2011
When you clear your cookies in Firefox, all data that is saved by webpages onto your system will be erased. For example, if you selected for a website to automatically log you in, it will no longer do that since your login information is no longer stored in that specific cookie. However, clearing your cookies is a good way to speed up your system, since you likely have thousands of irrelevant cookie files saved onto your computer's hard drive.
To clear your cookies, click on the "Tools" menu in the menu bar at the top of your browser window and then select "Options"; if you're not using the menu bar, click on the "Firefox" button at the top-left corner, and then click on "Options".
A dialog titled "Options" will appear, so select the "Privacy" tab at the top of that dialog; around the middle of that same window, you’ll see a link that says "remove individual cookies", so click on it.
After clicking on that link, another dialog titled "Cookies" will appear, this time with a list of the cookies stored on your computer. To remove individual cookies, select them and then press "Remove Cookie". If you wish to clear all cookies, press "Remove all cookies" at the bottom of the dialog.