question

hi
i just bought my arduino uno, and i have question.
is the program that i upload to the arduino save in the board, i mean after i upload the sketch and switch off then switch on the board the program still the same, if yes, there is anyway to clear the arduino?

The program remains.

What do you mean by "clear"?
The boot loader will always be there.

To clear your previous program load an empty program.

void setup()
void loop()

Weedpharma

The old sketch will be replaced when you upload a new sketch. There is no need to "clear" the chip. Most Arduinos come with the "Blink" sketch pre-loaded so if you really want to "clear" your Arduino you could upload that example.