Excess under-arm tissue
From the photos you included you appear to have both excess skin and fat under your arms. Removal can range from less invasive procedures such as Coolsculpting, or more invasive surgical procedures such as liposuction or excision of the tissue. What you choose depends on your goals, and if your goals are just less bulk and you don't mind the excess skin, you can stick with one of the less invasive solutions.
Extra mammary breast tissue treatment
You have extra breast tissue in the axilla. Best treatment option is direct excision of tissue. Seek a board certified plastic surgeon for consultation. Best, Dr. Yegiyants
How can I remove the extra tissue under my underarm?
Thank you for the question.
Yes, it is possible to excise axillary breast tissue. In my opinion, this is best done by direct excision ( as opposed to liposuction surgery). Often, it is necessary to remove overlying skin also to improve contour of the area.
I would suggest in-person consultation with a well experienced board-certified plastic surgeon who can show you examples of similar patients he/she has taken care of.