Relieving the fuel pressure on your Pathfinder is done by removing the fuel pump fuse, starting the engine, and let it idle until it stalls. This will relieve the pressure in the line and then you can drain the remaining into a fuel-safe container. Just curious, why is it you think you got a tank of bad gas? Is it not running correctly? Do you have any warning lights illuminated now?
Be very careful with the fuel system. Protect your eyes anytime you open a fuel line in case any squirts out. If you loosen any of the banjo fittings, those copper washers (seals) will need to be replaced. They are made to be 1 time use