Why did coca-cola stop putting cocoa nut in coke 1907(not sure on actual year?

From Wiki:

Coca-Cola did once contain an estimated nine milligrams of cocaine per glass but after 1903 Coca-Cola started using, instead of fresh leaves, "spent" leaves - the leftovers of the cocaine-extraction process with cocaine trace levels left over at a molecular level. However, as cocaine is one of numerous alkaloids present in the coca leaf, it was nevertheless present in the drink. Today, the flavoring is still done with kola nuts and the "spent" coca leaf. In the United States, there is only one plant in New Jersey authorized by the Federal Government to grow the coca plant for Coca-Cola syrup manufacture.

Also check:
Straight Dope: http://www.straightdope.com/classics/a2_033.html
Lew Rockwell: http://www.lewrockwell.com/jarvis/jarvis17.html

The new soft drink was one of many concoctions in that era containing cocaine, which was being touted as a benign substitute for alcohol. Coke, in fact, was promoted as a patent medicine, which would "cure all nervous afflictions--Sick Headache, Neuralgia, Hysteria, Melancholy, Etc...."

How much cocaine Coke actually contained and how much kick you got from it is not known (a Coke spokesman today says the amount was "trivial"). But for years Southerners called the stuff "dope" or "a shot in the arm," while soda fountains were called "hop joints" and Coke delivery trucks "dope wagons."

In the 1890s, however, public sentiment began to turn against cocaine, which among other things was believed to be a cause of racial violence by drug-crazed blacks. In 1903 the New York Tribune published an article linking cocaine with black crime and calling for legal action against Coca-Cola.

It never had coconut.

The cocaine wasn't completely out of Coke until 1929. And it wasn't in a great enough dosage to get high, although you probably wouldn't pass a urine drug test. They still use coca leaves to make Coca-Cola, which are completely cocaine-free!

Because the side effects of cocaine were discovered and cocaine became illegal.