Type '''about:addons'''<enter> in the address bar to open your Add-ons Manager. Hot key; '''<Control>''(Mac=<Command>)''<Shift> A)''' In the Add-ons Manager, on the left, select '''Extensions.''' Mouse on top of the add-on. There should be a '''Remove''' button. If there is still a problem, Start '''[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Firefox in Safe Mode]''' {web Link} by holding down the '''<Shift><br> ''(Mac=Options)'' ''' key, and then starting Firefox. A small dialog should appear. Click '''Start In Safe Mode''' (not Refresh). Is the problem still there?