Grip one of the clear fuel tubes near where it connects to the petcock and squeeze it completely closed.

Pull the tube directly away from the petcock nipple to remove it.

This may require some force due to suction within the tubes.

Use a pick tool to lift one end of the tube up to break suction if needed.

Residual fuel in the fuel lines may leak out after the tube is removed.

Disconnect the second fuel tube from the petcock.