It's from a light indicator for my toyota security system.
Since I cannot see the white connector in the image, I'm assuming the white connector is like the blue one. To that end, you need to press the beveled piece (red arrow). This should release one part from the other.
EDIT: To assist in getting them apart, press them together before you press the beveled piece.
You can also try using a very small flat blade screw driver to pry the obvious (i'm guessing it might be obvious) prong up before at the same time pulling it apart.
If you can't figure it out I strongly suggest you get a magnifying glass and take a good look at it to see what gives. You should, under a magnifying glass, be able to wiggle it and see which parts are molded to which parts, and which parts move against which parts. Also you should probably be able to see the mechanics of it enough to figure out what to do.
My rule of thumb is that if you can't figure it out, look with your eyes a bit closer.