Arduino Uno First Program Please help with this error.
Arduino: 1.8.10 (Windows 10), Board: "Arduino Uno"

Sketch uses 882 bytes (2%) of program storage space. Maximum is 32256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes for local variables. Maximum is 2048 bytes.
avrdude: ser_open(): can't open device "\.\COM4": Access is denied.

Windows 10 Pro
Arduino UNO ATmeg 328P-PU
Have never been able to Upload a sketch. 
Pin 13 and Orange LED blink at 1 second
Welcome to the Stack Exchange and on the Arduino World.

Just a note: Since yesterday there is a new version of Arduino IDE (the last version is now 1.8.11).

When you buy an Arduino, a default sketch is already present. This will blink your LED (pin13) with a 1 second interval. This just mean that your Arduino is working and has a bootloader.

To program it, you need to know which COM port is created for your Arduino module:   


Press WIN-'R' (execute application)  
Write devmgmt.msc


Check the COM port to see wich COM port was used for your Arduino.

This is the only cause, the message could appear if you use a standard USB-cable connected to your standard Arduino UNO board.