Can the pigmentation on my underarms be completely removed?

I'm worried because the pigmentation on my underarms seems to be getting darker lately.

I suspect there might have been irritation from consistent hair removal, or perhaps it was due to other friction; I'm not entirely sure of the exact cause. I would like to know which treatment was most effective for underarm hyperpigmentation.

I would like to hear opinions from those who have received the treatment regarding how much existing pigmentation can be improved.

I am curious how many treatment sessions are usually required to see results and how long the effects last.
How you helped to get rid of it completely

Are there any home care treatments or management methods you have tried personally that were helpful or effective?