There is a clinic of skin doctor located at a walking distance away from my daughter.  So, I intended to make an appointment with the doctor some time when I repair to my daughter place.  But she stopped me to do so; instead, she recommended me of taking a DIY method. 

She then ordered a "skin tag removal kit" online, in which it contains a cone, a slim stick with pulling thread, and skin wipers, to cover the tag of 5mm to 12mm.  I think those stuff helps to "dry" the skin tag and then let it die and eventually be removed from your skin.  But they are too small and too delicate for a senior like me to do the job alone.  So, my daughter did it for me.

After three days, the tag has gone, almost imperceptibly.  It works!