Firefox (iOS)

1. Open the Firefox app.

2. Tap the three lines (≡) icon in the bottom right corner.

3. Select Settings.

4. Scroll down to the Privacy section and tap Data Management.

5. Tap Website Data.

6. To remove all site data, tap Clear All Website Data at the bottom. 
   — or —
   To remove data for specific sites:

   • Tap the checkboxes next to the sites you want to delete.

   • Then tap Clear Items at the bottom. 

7. A confirmation popup will appear saying:
   "This action will clear the selected items. It can't be undone."
   — tap OK to confirm or Cancel to abort.

8. Close Firefox and open it again for the changes to take effect.

How to close the app: swipe up from the bottom of the screen (or double-press the Home button), find Firefox in the app switcher, and swipe it up to close.