Nice Wallysb.
Just quoting myself:
"run it as sudo if it gives you attitude. And maybe make a copy of the file first."
I had reason to try this on a few files stuck on fibre attached today and it was super cool.
chmod 777 doesn't always clear stubborn locks but worth a try if you need to do other things to the file.
PS- I've seen that graphic on T-shirts. Cracked the IS team up. Everyone else just starred off.