If you don’t want to use the Suggest feature on your browser and want to disable sponsored suggestions and ads, then here is a step-by-step for the same.
Step 1: Open Mozilla Firefox web browser on your computer.
Step 2: When Firefox opens, click on the hamburger menu or the three lines icon from the upper right corner of the browser.
Step 3: From the drop-down list, select the “Settings” option.
Step 4: In the Settings page that opens, click on “Privacy & Security” from the left sidebar.
Step 5: Now, scroll down to the “Address Bar” section and uncheck the box for “Contextual suggestions” and “Include occasional sponsored suggestions”.

That’s it. You will now have to close the Mozilla Firefox web browser on your computer and reopen it for the changes to take effect.
Now, when Firefox opens again, the sponsored suggestions and ads in Mozilla Firefox should be disabled.