If you are ever in a pinch, and need to remove a nut, but do not have the right size wrench, a hammer and metal chisel will do the trick. I’ve used this method many times in salvage yards, when I did not have the correct wrench. Be sure to wear safety glasses, as parts of the nut may break off.
All you have to do is place the tip of the chisel onto the flat edge point of the nut. Now, strike the chisel with the hammer in the loosening direction. You will need to continue working the nut off in this manner. If the point on the nut breaks off, just move to the next point on the nut.
NOTE – THIS METHOD WILL RUIN THE NUT. (I only use this method as a last resort, when I am in a pinch).