How to remove this annoying profile button?

I had the same button show up after I accidentally created a second profile, and the thing that got rid of it for me was opening about:profiles and deleting the extra profile from there. I made sure my main profile was set as the default first, then restarted Firefox, and the button was gone. It is worth checking whether a second profile is still listed there, since the button only sticks around while there is more than one.

About, Sync your data everywhere (screenshot) https://support.mozilla.org/en-US/questions/1607352#answer-1859004 https://connect.mozilla.org/t5/firefox-labs/can-you-stop-putting-adverts-in-the-menus/m-p/145375/highlight/true#M5394

''<p>Agent virtuel [[#answer-1859365|said]]</p>'' <blockquote>Bonjour Introduction, please read. Firefox is a work in progress and, to allow for continuous innovation, Mozilla cannot guarantee that future updates won’t impact these customizations, https://support.mozilla.org/en-US/kb/firefox-advanced-customization-and-configuration, https://support.mozilla.org/en-US/kb/contributors-guide-firefox-advanced-customization Take a look at https://www.reddit.com/r/FirefoxCSS/comments/1vyau4n/comment/p5vnv1a If you wish to try <blockquote>'''#appMenu-profiles-button,''' '''#profiles-menu {''' ''' display: none !important;''' '''}''' </blockquote> Copy/paste the code into your Notepad Save Type: All files '''userChrome.css''' Create a '''chrome''' folder Move userChrome.css to your chrome folder Go to your profile folder https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data Move your chrome folder to your profile folder Go to configuration editor https://support.mozilla.org/en-US/kb/about-config-editor-firefox Enter a search term '''toolkit.legacyUserProfileCustomizations.stylesheets''' Double-click on the preference, to set its value to '''true''' And restart Firefox Just to see. Without userChrome.css - With userChrome.css </blockquote> Thank you. This one worked! I shouldn't have to go into the code and mess with it in order to remove something that was put in without permission, but I digress. Thank you for figuring this out. And on top of making it so I can no longer even edit profiles due to the other settings in about:config , I shouldn't ever have to worry about profiles again