Cannot delete a file in a disabled Time Machine backup

Hi,

I have a file on my system that I cannot seem to delete. It is inside a local Time Machine backup that is no longer used. Time Machine keeps local backups when not connected to the external backup drive, but I have disabled these using 'sudo tmutil disable local'.

That caused Time Machine to rename the local backup folder /.MobileBackups/ to /.MobileBackups.trash/, and I assumed that this folder would be removed when I restarted the computer. But it wasn't.

When I tried to delete the folder in Terminal (with 'sudo rm -rf /.MobileBackups.trash/') I see that there is one file remaining in the folder, a few levels down, and the 'sudo rm -rf' command is unable to remove this file. It says 'rm path/to/file: Operation not permitted'.

Any ideas for how I can remove this file? I obviously tried 'sudo rm', and I've also tried using 'chflags nouchg /path/to/file' to try to unlock the file, then removing it again, but that didn't work either.

The file is an app called CrashPlan.app (you may have heard of it) which is residing in /.MobileBackups.trash/Computer/2014-11-02-150317/Volume/Applications/CrashPlan. app'

Thanks in advance for your help!