What is a one-sentence summary of the following article?
Click or double-click the Firefox app, which resembles a blue globe with an orange fox wrapped around it. It's in the top-right corner of the page. A drop-down menu will appear. This option is in the middle of the drop-down menu. It's near the top of the menu. This is near the top of the menu. Clicking it opens a pop-up window. Click the "Time range to clear" drop-down box, then click a time span (e.g., Last Hour). Selecting Everything in the drop-down menu will ensure that all of your history is cleared. It's a downward-facing arrow to the left of the "Details" heading. A menu will appear. You'll find this at the top of the menu. You can uncheck every other box in this menu if you please. This option is at the bottom of the menu. Doing so clears your Firefox history for the selected time range.

Summary:
Open Firefox. Click ☰. Click Library. Click History. Click Clear Recent History…. Select a time range to clear. Click the "Details" drop-down icon. Check the "Browsing & Download History" box. Click Clear Now.