Is R2-D2 droid smartest?

Because droids learn and grow, R2-D2 has grown smarter and more intelligent without a memory wipe. But he has also been associated and working with some of the most powerful and knowledgeable people in the Galaxy (Anakin most specifically, but he was on missions with many other Jedi as well).

How do you turn r2d2 off?

Answer: Keep the knob in the front pressed till it turns off.