Jacob, I ran into a similar problem trying to delete a couple of folders from my Public/Shared Music folder, stating I needed permissions granted by Unix User/root to perform the required action. I found a way around it hopefully it may work for you:
Go to the configuration of the drive
Open a browser / explorer and navigate to: ftp://admin@
When prompted enter the password for your admin account for the Network Storage Manager
Navigate to the folders you require to delete and attempt to delete
I had tried a number of times to figure this problem out and the approach above finally worked for me.