Force delete objects on a NAS share?

Hi,

I've got a NAS drive (ReadyNAS) that has old backup files on it I'd like to get rid of. I either get "object is locked" or "unsufficient priviliges" messages when I try to drop the folder in the Trash, depending on which account I use to map the drive (I've got one user and one admin account). I get the message on different files that are causing this and I've tried to press alt while dropping the folder on the Trash. How can I force delete the folder with these stubborn objects?

/Mans