I found a directory on my machine called "Previous System" that looked old and useless and I tried to delete by dragging to the trash and emptying the trash. That failed to delete the directory, because emptying the trash gave me messages such as The file 'Applications' is in use. or The file '.MobileBackups' is in use.
So I dragged that directory out of the trash and went into the terminal to delete it, but it seems undeletable. For example:
$ cd ~/Desktop
$ sudo mv Previous\ System prevsys
$ sudo rm -rf prevsys
rm: prevsys/.MobileBackups/Computer/2014-10-20-143930/Volume/Applications/CrashPlan.app: Operation not permitted
rm: prevsys/.MobileBackups/Computer/2014-10-20-143930/Volume/Applications: Directory not empty
rm: prevsys/.MobileBackups/Computer/2014-10-20-143930/Volume: Directory not empty
rm: prevsys/.MobileBackups/Computer/2014-10-20-143930: Directory not empty
rm: prevsys/.MobileBackups/Computer: Directory not empty
rm: prevsys/.MobileBackups: Directory not empty
rm: prevsys: Directory not empty
$ cd prevsys
$ sudo ls -l
total 0
drwxr-xr-x+ 3 root wheel 102 Nov 18 2013 .MobileBackups
$ sudo cd .MobileBackups
$ pwd
/Users/blah/Desktop/prevsys
I've never seen a directory that I can't cd into as the superuser, so I'm not really sure, how do I get rid of this thing? Thanks.