How to delete ALL previously used libraries and start from scratch

[in0]

We can help with that, but it is probably unnecessary. I have explained the problem in your other thread:

Another Pre-compiler can't find, or install custom library issue

First of all, please immediately halt all the other efforts that are in progress. They are all pointless and will only result in additional problems and confusion. This is the sole problem: This is not a valid location for the sketchbook. Windows has strict security controls on the C:\Program Files (x86)\ folder, which is what caused this "AccessDeniedException" error when you tried to install libraries to a path under it: Please do this: Select File > Preferences... from the Arduino IDE…