remove fast start tab malware

Hi I am having trouble removing fast start tab from my favourite firefox.

I have not activated the usage of my norton 360 since the last expiry date until the malware hit my laptop.

After activation and scanning and cleaning with the help of norton internet security, the fast start tab in my firefox browser has not been eradicated.

See the pic below how the fast start tab looked like.

Please advise the solution. Thank you

Clement Yap