CIFS Shares and permissions off of /backup

A long time ago(Pre-boost) and on a DD690 I created a share off of /backup called nw(/backup/nw).   On this share I was using a userid called nwbackup.    Since that period I moved to DDBoost and later had EMC migrate my data to DD2500's.  Here is where the problem is.  I finally had a release on backups I was holding and want to get rid of the backups in that share.  I no longer have permissions and see a SID where the owner should be.   My thought is that when it was migrated the USER ID and associated SID no longer were tied together.  How do I change the permission on the folder?  No matter what I do I do not have permisisons.