This article shows an upcoming version of Firefox for iOS, so yours might look different. Please update in a few weeks to get these features.

Firefox stores websites you've visited in your history as you browse the Web. Follow these steps to delete your history.

At the bottom of the screen, tap the menu button (the menu will be at the top right if you're using an iPad):
Tap Settings in the menu panel.
In the Firefox Settings menu, under the Privacy section, tap Clear Private Data.
Tap the switch next to the types of information you'd like to remove.
Tap the Clear Private Data button.

Caution: Clearing your private data will close all your active tabs.

What types of information can I remove?

Browsing History - addresses and cached text for websites you've visited. Clearing this will remove these websites from your top sites.
Cache - parts of web pages that are stored in the browser to make them load faster the next time you visit.
Cookies - files that contain information about your visit to a website, including site preferences and user information.
Offline Website Data - Files a website stores in your device (if you've allowed it) so you can continue to use it offline.
Saved Logins - Records of usernames and passwords.

Clear browsing history in Firefox for iOS