I'm 16 and i have a naturally high forehead and i was wondering what is the best way to make it lower?

Thank you for your question.  Technically, this is certainly possible although I would not expect 2 cm of lowering.  One cm is a more realistic goal to shoot for because of the lack of elasticity of the scalp.  This is done through a trichophytic incision.  Having said that, I would not recommend such a procedure in a 16 year old.  Your facial structures are still maturing.  You may still be growing as well.  Finally, this is a decision that will make a significant alteration to your appearance and should not be taken lightly.  It will also result in temporary numbness to the scalp behind the incision.  Personally, I would not perform an operation like this without a compelling (i.e. reconstructive) reason before the age of 18.  I hope this helps.

Greetings,
It is hard to find doctors for forehead lowering since they need to be experts in 2 areas.  First of all, doctors need to be experts in facial plastic surgery or plastic surgery to lift up the scalp area and advanced along the forehead.  The galea is released during this.  A key component is hiding the scar along the border of the scalp.
The second component is being an expert in hair transplantation.  The hairline is lowered and the scar is camouflaged through hair transplants. 
Look for a surgeon specializing both plastic surgery of the face and who does hair transplants.
Best,
Dr. Anil Shah 

A naturally high hairline can be lowered. In male patients, I would recommend waiting until the early to mid 20's before considering any surgical procedures, and I would still most likely recommend hair transplants in any male patient. In a female patient, hair transplant is still an option, but another great option is hairline lowering surgery (also known as a hairline advancement, scalp advancement, forehead reduction, etc). Be sure to see an expert in both facial plastic surgical procedures and hair restoration.All the best,