Arduino Problem (Response Delay)

Hi guys I don’t know if you encounter this problem with arduino, but I want to share this problem and the things I’ve done to solve it.

Problem:

I upload one of the example program(02.Digital / Button) to “arduino UNO”. Base on the program when  port 2 receives 5v port 13 must release 5v and when port 2 receives 0v, port 13 must release 0v. When I try to put 5v to port 2, port 13 releases 5v but when I remove the 5v supply to port 2, port 13 is still “ON” and it turns “OFF” after a few seconds. The question here is “ the program doesn’t contain any timer to delay port 13 to turn “OFF”, then  why port 13 is delayed?”, I also try to change the ports on the program, but the response of the program is still the same.

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