Cookies are small pieces of information that some websites store on your computer. Cookies may contain authentication data, your session details, browsing history, etc.

It is recommended to regularly delete cookies from your browser to prevent websites from tracking you.

To delete cookies from Firefox follow these steps:

• Open the Firefox and click on Options.
• Choose the Privacy icon on the top. Click on the cookies option and then click on view cookies.
• This will show you the list of all the cookies that are present on the hard drive currently via Firefox.
• To delete a single cookie, select the cookie which needs to be removed and click on remove button.
• To delete all the cookies at once, click on the Remove All button.
  
  

Note: deleting cookies from Firefox wouldn't delete cookies from other browsers.