Same way you do on a car.
with a nut splitter
If your lucky you can pound a smaller socket onto the nut and remove it. More often than not you need to weld a larger nut onto the stripped one, then turn the larger nut. Most tire shops can help if you don't happen to own a mig welder.
Sears sells a special socket to remove rusted, stripped and broken nuts.
Best just to remove the nut and replace it with an new one, or grab a pair of pliers and tighten it that way if you absolutely need to.
Drill it buy new hex nut. If unable to find new hex nut. Buy new ...
It unscrews and it is plastic. Discount Tire stripped mine out with an impact. Now I am looking for a new one.
Use an impact wrench to either remove it or break it. Then replace the lug. Cut it off with a chisel if you can't get a socket on it.
Stripped nut can not be reused. If the nut is the kind that was put onto the hose end before the hose fitting was crimped, then the entire hose will have to be replaced along with the nut.
Not aligning the threads up correctly and forcing the lug nut onto the wheel stud will strip the lug nut.
To remove a pressed-in stud, you usually stack up a few washers and crank the stud out with an impact wrench on the nut. If the threads are completely stripped all the way down, you may have to take the head to a machine shop and have the stud drilled out and tapped for a screw-in stud.
There is a nut under the plastic cover at the base of the arm.
I'm assuming you mean a stripped nut? If so, it's best to simply replace it. They cost about 50 cents. If your axle or kingpin is stripped, you need a tool called a re-threader. Simply apply the threader on the axle and retool the metal to work for the nut. If your kingpin is stripped, I'd suggest getting a new one, or possibly getting a new baseplate/kingpin combination. Otherwise, get new trucks!