if you can drag them to the trash, hold down the option key when you select empty trash. If you're trying to delete them from a file server and they are locked using the Finders locked flag, then you can select the file, select "Get Info" from the file menu, and then take the check out of the "locked" box.
if you mean locked as in you don't have permission to throw them out, you'll need to have the system administrator delete them. are you the system administrator?