Installation: 12 storeys deep

My newly installed Arduino IDE is not running, I suspect the reason is the \library directory that is 14 storeys deep and contains on the last but one floor a directory named ArduinoTestSuite and on the bottom floor the empty directory ‘examples’. I can’t delete this tree, so I’m asking you how I can proceed.

Well, about the only clue you've given is the '' which suggests you're on Windows of some sort.

Windows can't access any file if their complete file names (which includes the full path name) are longer than 255 chars.