The "Access is denied" error happens when the port is open in another application. Only one application can have a serial port open at a time so Arduino IDE can't perform an upload under these conditions.
Check to see whether you have any applications running on your computer that might use the port. If they are, close them and then try the upload again.
If the "Access is denied" error still occurs after that, try restarting your computer. In rare occasions, a glitch causes the port to get stuck open. This is one possible cause of the error. Restarting your computer restores the port to the normal working state and so fixes that particular cause of the error.