How to get rid of chicken skin under the arm?

Stop playing with your food!

Are you talking about Keratosis Pilaris?

Thank you for posting your question to the Ask Me Help Desk.

Here is a website for a little reading.
I found it quite interesting.

Chicken Skin

It says there is no cure but it is treatable and harmless so it would appear there is not too much to worry about.

Good luck!