I know there is no root user. You need to create SMB share and give the path above to directory which you want to delete and in share permission you can define run as root permission to a user fro AD  then map share and you would be able to delete the directory..  I have tested the same and it works.
I have configured a Isilon OneFS 7.1.0.4 system in Compliance mode, the compliance clock is all set etc. As compadmin, I have created a SmartLock directory, but I forgot to specify it as a compliance directory when I created it.  isilonc-1% ls -ld /ifs/data/dev/test drwxr-xr-x    2 compadmin  wheel  0 Oct 28 17:05 /ifs/data/dev/test isilonc-1% sudo isi worm info /ifs/data/dev/test -v SmartLock Info for: /ifs/data/dev/test  SmartLock Root Directory ------------------------ SmartLock Root Directory 65536 ---   Root Path: /ifs/data/dev/test   Type: SmartLock   Default Retention Offset: None   Minimum Retention Offset: None   Maximum Retention Offset: None   Autocommit Offset: None   Override Retention/Litigation Hold Date: None   Privileged Delete: Off  Now I want to delete it, but I get permission error even (a) it is not a compliance SmartLock directory, and (b) the directory is still empty. I have read a few threads related to this (e.g. [URL] or [URL] but I don't seem to have a affirmative answer removing such directory forbidden.  I'm still hoping I could delete it somehow, could anyone help?  isilonc-1% sudo rmdir test Password: Sorry, user compadmin is not allowed to execute '/bin/rmdir test' as root on isilonc-1. isilonc-1% sudo rm -rf test Password: Sorry, user compadmin is not allowed to execute '/bin/rm -rf test' as root on isilonc-1.
Unable to delete the SmartLock (Enterprise) directory on a Compliance Isilon