Follow this guide in order to clear the cookies and cache from your Firefox Web Browser.
Step 1 - Open Firefox and select the 3 horizontal lines in the top right of the window.
Step 2 - Select "Settings" from the drop-down menu that opens after step 1.
Step 3 - Select "Privacy and Security" from the left-hand side of the settings page.
Step 4 - Scroll down to the "Cookies and Site Data" section and select "Clear Data..."
Step 5 - Make sure that both "Cookies and Site Data" AND "Cached Web Content" are selected before pressing the blue "Clear" button.
Step 6 - Select "Clear Now."
Step 7 - Exit out of all Firefox windows to completely to restart your Firefox Browser, and you're done!
Special thanks to Laura Hughs for providing a starting point for this guide!