A small screwdriver, slipped into the hook at the end of the spring will allow you to stretch the spring off its mounting point. Put the shaft of the screwdriver through the hook, brace the tip against something solid in the fridge, then pry to stretch the spring until the hook is clear of its mounting point.
Have a couple of spotters and borrow a Golf Channel cameraman because when the spring comes loose, it's going to want to fly. Alternatively, have someone hold their gloved hands over the spring as you pry to contain it when it comes loose. The gloves will protect their hands from the force of the spring releasing and at most, it should drop down, bounce and roll only a foot or two so it'll be reasonably easy to find.
An alternative is to use a pair of needle nose pliers to do the same thing as you would with the screwdriver. The only difference is that you grab hold of the spring with the pliers and squeeze tight. When the spring comes loose, the pliers should hold it just fine so you won't have to go searching for it.
If you really want a tool specifically designed for removing a spring with a hooked end, go to your local auto parts store and ask them for a drum brake tool kit. It comes with a couple of weird shaped tools to remove springs exactly like the one in your first picture. The tools are quite strong as the springs in drum brakes are considerably stiffer than the one that closes your fridge door, so the tool will be quite up to the task.
Based on the picture posted after this answer was written, I've drawn in a screwdriver and a hand.
Put your screwdriver (the longer the screwdriver, the more leverage you get by pushing on the end of the handle - physics for the win!) through the hook on the upright metal piece, place your gloved hand where the yellow line is, then push the screwdriver in the direction pointed by the green arrow.
It shouldn't take a tremendous amount of strength to stretch the spring the 1/4" or less that it will take to get the hook out of the notch that holds it. Once the hook of the spring starts to move, the curve on the metal bracket should guide it up and the spring tension will do the rest of the job to remove it.
Do be aware that as the spring releases and compresses, it will pull the tip of the screwdriver (resting against the metal) back toward you. This could, potentially, pull the screwdriver out of your hand and might throw it back at you. It could also just slip out of your hand and land on top of the fridge, possibly rolling off the side and getting lost. One more little point to be aware of.