I'm guessing you are getting more than a little frustrated with all these different answers!  Here's my "2 cents" and I've have removed thousands of these on my asian patients over the years.  I don't recommend liquid nitrogen because it leaves a larger wound to heal than the size of the actual lesion because it's very difficult to do precisely.  Also, it often leaves a whiter spot after healing. While certain lasers are great for flat brown spots, most don't work well on raised seborrheic keratoses (SKs).  The ones that do are considerably more expensive than what I'm about to propose.  Shaving it off can work well but if the doctor shaves too deeply, it can leave a little divit.

 In my opinion, using a light hyfercator on setting #2 to 3 (most dermatologists have these) followed by using a light surgical currette works the best.  The SK will be gone, risk of scarring it very minimal, and healing is fairly rapid, usually 5-7 days.  We prenumb our patients so it doesn't hurt.  No sun for a month after and sunscreen every morning are a must.  Sometimes it's also a good idea to treat for 2 weeks before and sometimes after with a hydroquinone "bleaching"  cream to prevent temporary darkening depending on your climate and time outside.  I hope this helps!  Dr. I