I had the same issue. Was a little complicated but I opened the file's properties then changed the ownership to "Everyone" then edited permissions by ticking "full control" for everyone.
I think it did it for all system files though because I didn't have to redo the process for the other ones. I am half way through but will change the permissions back when I'm done. Also I didn't delete, I noted exact address paths before I cut and pasted them into another folder on the desktop (just in case it messes something up).