I'm not a FF user but you should be able to go to Manage Search Engines and remove it there. This is a standard FF functionality.
posted by x.15a2 Community Leader4 years and 28 days ago Link

Unfortunately,that doesn't work either..all greyed out.No option to remove.
After this,I'm thinking,"do I really need Firefox?"

But thanks for your reply.

Other ideas appreciated.:)
posted by annaheretoo 4 years and 28 days ago Link