How to Remove from Mozilla Firefox comes to your browser usually from downloading/installing free program. It will change your default search engine and homepage of your browser.

To remove from Mozilla Firefox :

Uninstall programs from your Windows
• Go to Control Panel--> Programs and Features
• Look for Search us com and uninstall it

Open Mozilla Firefox browser
• Type in address bar:    about:support   then click Ok or Enter
• See the Reset Firefox to its default state window (at the right), then Click Reset Firefox button 
will be a warning Are you sure want to reset firefox to its initial state ? Click Reset Firefox

• Restart Firefox, and see the result..