Hi, 1 - When you open firefox app on android, click the 3 dots icon next to your search bar. 2 - Click the "History" tab from the opened side menu. 3 - Click the trash icon on the top right corner. A modal will show up. 4 - In that modal you have 3 options: Last hour, Today and Yesterday and Everything. You can select one of them to delete your history and cookies. 5 - When you select one of the options from the list, click the delete button.

I hope it helps.