How to Remove unknown add-on from Firefox
Click on Tools or the Firefox menu icon on the top right of the browser and then select Add-ons.
Click on the Extensions tab on the left side in the Add-ons Manager page,
When all Firefox installed extensions are displayed, find the unwanted add-on and click on the Remove button to delete it.
Delete Gold-page.com from Firefox homepage
Click on Tools or Firefox menu icon on the top right of the browser and select Options.
Click on the General in the Options page.
Under Startup section, make sure “Show my homepage” is selected when Firefox starts. Delete Gold-page.com from the Home Page box if it exists, and then enter the address of your desired homepage.
Set your default search engine
Click on Tools or the Firefox menu icon on the top right of the browser and select Options.
Select Search on the left side of the Options page.
Under Default Search Engine, click on the drop-down menu ▼and then choose the search engine you want to set as the default search engine.