You can remove the search engine bar in the address bar drop down list by setting this pref to false on the about:config page.

• browser.urlbar.oneOffSearches = false

You can use code in userChrome.css remove all suggestions from the address bar drop down list. Add code to the userChrome.css file below the default @namespace line.

• http://kb.mozillazine.org/userChrome.css
• https://www.userchrome.org/how-create-userchrome-css.html
• https://www.userchrome.org/what-is-userchrome-css.html

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

/* remove all items from the urlbar drop down */
#PopupAutoCompleteRichResult {display:none !important;}

It is not that difficult to create userChrome.css if you have never used it.

The first step is to open the "Help -> Troubleshooting Information" page and find the button to access the profile folder.

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

You can find this button under the "Application Basics" section as "Profile Folder -> Open Folder". If you click this button then you open the profile folder in the Windows File Explorer. You need to create a folder with the name chrome in this folder (name is all lowercase). In the chrome folder you need to create a text file with the name userChrome.css (name is case sensitive). In this userChrome.css text file you paste the text posted.

In Windows saving the file is usually the only time things get more complicated because Windows can silently add a .txt file extension and you end up with a file named userChrome.css.txt. To avoid this you need to make sure to select "All files" in the dialog to save the file in the text editor using "Save File as".

You need to close and restart Firefox when you create or modify the userChrome.css file.

I already had a userChrome.css file from fixing other problems that apparently can't be solved by changing settings in prefs.js (and fortunately, I don't use Windows, so I don't have to deal with its problems on top of Firefox's).

Your solution worked. Thank you SO much!

The browser.urlbar.oneOffSearches = false ALMOST works.

The blue bar is gone as are the suggestions but a empty white bar about ¼ the height of the blue bar still drops down. :(

In Firefox 68 you can use this code to hide the urlbar results drop-down list.

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

#urlbar-results { display:none!important; }