Why did anakin skywalker kill younglings?

Because he is a cold hearted Sith Lord *(not a lord at this point) that will obey Palpatine(the emperor).

He also is convinced by Palpatine that the Jedi Order is evil *(no)

**(he kills the younglings because it is a test from his new master, if he had not killed them he would have been killed and, in his mind, he wouldn't be able to learn how to save Padme. At that point Anakin would have done anything to save Padme and if Palpatine could teach him how he was willing to do anything and everything he was asked.)