Within the browser, go to the Add-Ons manager and remove it there.
Next, go to Control Panel -> Programs and Features -> and unisntall any references to the software here.
Download and install Malwarebytes free edition and perform a full manual scan of your system. This will remove many forms of Adware/spyware/PuPs from your system. Should should run at least one additional program from the following:
Spybort Search and Destroy, Adaware (free) from Lavasoft, SuperAntiSpyware, AdwCleaner
When that is done, you should be free and clear of Adware/spyware.