Access is denied. Error compiling for board Arduino/Genuino Uno
High likely one of the intermediate/binary files is in use. For example:


When you have it already opened in a debug session
Having it opened in multiple instances of your IDE
Having it opened in another application
Having closed an application that locked the intermediate/binary file(s).


What you can do:


Close the debug session
Close all applications related to the project
Restart your computer