What way do you turn the nut to remove the blade on a Toro self-propelled lawnmower?

To remove the fastener that holds a mower blade on, turn the fastener in the direction the blade rotates to cut the grass. Look at the blade, find the "leading" or sharp edge, and, while holding the blade, turn the fastener in that direction. There is a good reason that this is always true. It has to do with the physics of the machine. Imagine the fastener being "held in place" to stop it from turning as the machine starts. With the machine starting to turn, the fastener will tighten. The last thing you want is to have the fastener become loose when the machine is running. The blade could kill or injure someone if it came off. That's why the fasteners that hold the blades on these machines always come loose when turned in the direction the blade rotates.