In Windows there is a maximum 255 character path name. You can create files and folders with longer paths but they will become inaccessible and undeletable. Sometimes this happens if you extract an archive containing long file/directory names. Actually it is a pretty good way to frame someone; just make them extract an archive with a directory called “bomb making plans” and a file with a really long name inside it and they will be unable to remove it from their PC.
Fortunately there is a way to remove such files and directories, as long as you have 8.3 name creation enabled (it is by default). Use “dir /X” to find the short name of each item you can’t access and use “rename <short name> a” to change its name to “a”. If it is a directory you may have to enter it and do the same for any paths below it. Windows can’t even open a directory that contains other files or directories with long names so often the problem is two or three levels deep.