just figured I would show the location of the radiator drain and plug on a 2009 Chevrolet Aveo LT from the US (LXV engine), since I know I struggled to find the location of it when I seached online. It is located on the driver side of the engine, attached to the radiator. I used a combination wrench (I think 13 mm) to get it loose, it's a very tight fit down there I was unable to use a socket wrench.
It really helps to place a jackstand on the front driver side of the car to make the plug easier to remove. To remove the most coolant I would recommend removing any jackstands from the front of the car once the plug is loose and draining, placing a jackstand on the opposite side of the driver on the rear, and letting the coolant drain until it doesn't drain anymore.
Once I loosened the plastic drain plug enough, I was able to use my thumb and index finger to loosen the plug, which really made it faster to remove and screw in afterwards. Coolant comes out of that black rubber nipple. If you loosen too much like I accidentally did, the plug will pop off, which makes the coolant drain more quickly but way more messy.
NOTE that the picture got loaded sideways. Rotate the picture clockwise 90 degrees to get what it would look like under the car.