Wrinkled Arm Skin? Without a photo my guess would be ThermiTight RF treatments, in 3 sessions at cost of $5, 000 total..
Fish or fish oil. The most common cause of "chicken skin" is a deficiency of omega 3 fatty acids found by eating fish- esp. Fish from cold waters like wild salmon or sardines. You could also take a fish or krill oil supplement. Flaxseed oil may help as well but many need fish oil. Sometimes this can also be related to zinc deficiency so consider zinc, or even better, a multivitamin that has zinc.
Pigmentation. Some persons are born with darkly pigmented skin especially on the creases - underarm, elbow crease, groins. Chicken skin maybe caused by plucked hair. I suggest you consult a dermatologist for help.
No home remedies.? Have you lost weight, surgery to tighten skin on the arms leaves significant scars.
What's the best way to get rid of armpit hair to avoid them and having chicken skin and the best way to treat chicken skin, and dark underarms.
Depends. I'd recommend using a tweezer, or waxing or having it lasered off. I'm not too sure what chicken skin is!