Can't delete files

Hi there, we got footage from a Sony F800 card, transferred it to the ISIS and now I am trying to delete the

folder as we are done with it and am getting the following error:

File Access Denied

You require permission to perform this action

You require permission from S-1-1-0 to make changes to this file

ALIAS.XML

Type: XML Document

Any ideas would be great, thanks

Irene