Deleting locked files from a network drive

So many problems I run into come down to permissions. Here is the latest one.

I have a LacCie network hard drive. The back-up software I have (just the LaCie stuff) does total sequential back-ups rather than adding and removing from a restore file. This means that the network storage can fill up pretty quick.

The backup protocol simply takes my home folder and copies it to the drive.

When I come to try to delete a backup using Finder, I am first told that this is an immediate delete (no trash), and then told some time later that one of the files is locked. This is game over. When I check the permissions on the locked file, I find that it's read only. The items
affected are always settings files in the Library folder.

So, in Terminal, is there a way for me to delete this stuff quickly? for instance, is there a sudo command that lets me do it? I tried sudo rm -rf *.plist (as an example) seemingly to no avail.

Thanks for any advice.

Nige.