I tried to remove the supporting wheel of my son's bike the other day, it's quite easy to remove one but the other gave me quite a bit trouble - the nut is rounded thus can't be secured by a wrench. The bike, the nut, and the tools I used to try are shown below. I looked up online and found some links which look promising but not sure if they are fisible in reality, like this one on youtube https://www.youtube.com/watch?v=R5d0Bgvjmlk
Can anyone kindly help out? Also, on the left side of the bike, which direction is to loosen the nut? Counter-clockwise, right?