The Arduino 15 folder is where the IDE stores its data, from your IDE preferences, to the cores for the boards you have installed.
This folder is available in the following paths:
- On Windows
- Standard IDE:
C:\Users\{username}\AppData\Local\Arduino15
- Windows app:
C:\Users\{username}\Documents\ArduinoData\packages
- Standard IDE:
- macOS: /Users/{username}/Library/Arduino15
- Linux: ~/.arduino15
Please note that this folder is usually hidden and you will need to enable the view to be able to interact wit it. To do so, just check the box in:
Start > File explorer > View > Show/hide advanced settings > check Hidden items
.