What tool is needed to remove fuel line?

Since I do not know the year or model of the vehicle, I am assuming you are referring to the quick connect type fuel line fittings on most Fords. There are inexpensive removal tools available at most automotive stores. (Give them the make and model of the vehicle as there are different types and sizes of connectors) The tool slides onto the fuel line, by pushing the tool into the fitting it releases the fingers in the fitting. Make sure the fitting is clean and well lubricated as dirt can prevent it's release.