The fuel lines that feed the fuel rail are not screw on nut fittings, both the pressure & the return are disconnected with a set of fuel line/ac disconnect tools.
The pressure line is near the centre at the back of the engine. One pulls off the engine cover & you'll see the fuel rail. Once you've disconnected the line you'll need a lengthy section of garden hose to slip over the fuel line end & tape it up to prevent any leaking & feed it into a container size of your choosing. Now you can bypass the relay to power up the fuel pump to drain the tank.