I uploaded the examples 'blink'and 'fade' on my Arduino Uno.
I want it to get back original state because its purpose is not programming(actually it is in the neuroscience experiment package).. 
Is there anyone who could teach me how to remove or cancel uploaded example library..?
/*
Blink
Turns an LED on for one second, then off for one second, repeatedly.
Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO
it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN is set to
the correct LED pin independent of which board is used.
If you want to know what pin the on-board LED is connected to on your Arduino
model, check the Technical Specs of your board at:
modified 8 May 2014
by Scott Fitzgerald
modified 2 Sep 2016
by Arturo Guadalupi
modified 8 Sep 2016
by Colby Newman
This example code is in the public domain.
*/
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin LED_BUILTIN as an output.
pinMode(LED_BUILTIN, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}
This was the 'blink' example on Arduino editor website.
New Arduinos are AFAIK factory-tested with the Blink sketch.
You can't 'remove' a sketch.
But if you upload a new sketch, then the old one is automagically overwritten.
Sketches and libraries (many) are stored on your computer, not on the Arduino.
They are only used at compile/upload time.
Leo..
If you want the Uno to appear to do nothing, you can upload File > Examples > 01.Basics > BareMinimum. In any recent version of the Arduino IDE, you can also get that same sketch via File > New.
I suspect that OP overwrote the sketch that was on the Arduino, and now wants to get it back on there without having the original code. That is not going to happen. Fess up, and get the proper owner to upload the sketch again.