Firefox: Clear Recent History
In Mozilla's Firefox browser, you clear the cache from the Clear Recent History or Clear Data area.
The Ctrl+Shift+Del (Windows) or Command+Shift+Delete (Mac) keyboard shortcut is the fastest way to open the Clear Recent History screen, which looks like this:
Don't forget to choose Everything from the Time range to clear options, assuming that's your intent.
To get to the Clear Data screen through the menus, do this:
In Firefox's menu button (the three-lined hamburger icon), select Options.
Choose Privacy & Security from the left.
Select Clear Data in the Cookies and Site Data area.
If you scroll down a bit and choose Clear History, you'll get to the same screen that the shortcut above takes you to.
In the Clear Data screen that opens, select Cached Web Content.
CLEAR CACHE IN THE FIREFOX MOBILE APP
To delete the cache in the Firefox mobile app:
Tap the three-line menu icon at the top (Android) or bottom (iOS) of the app and choose Settings in the menu.
Select Clear private data on Android, or Data Management on iOS.
Enable the Cache option.
Choose CLEAR DATA on Android. If you're on an iOS device, select Clear Private Data and then confirm with OK.
For more information on how to clear your cache or if your browser is not listed here, check out this article.