Deleting libraries is done by deleting using the operating system (Windows Explorer). They are in the libraries folder in the sketchbook folder. But if you just started, that folder is probably empty.
It sounds like a corrupted install. Some possibilities that might solve the problem.
- Uninstall the IDE, delete C:\Users\yourname\AppData\Local\Arduino15, install the IDE. FGor the latter, I would download a new copy.
- Download the zip version of the IDE and extract it to a convenient location. In the directory where you extracted it to, create a directory called portable. Start the IDE by double clicking the exe in the directory where you installed it.
The portable install will make sure that there is no interference from or with other IDE installations on the PC; this is just to make sure that you basically start with a clean slade.